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THE DUCTUS ARTERIOSUS IN THE HUMAN FETUS AND NEWBORN INFANT

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Xerox University Microfilms
300 North Z eeb Road
Ann Arbor, M ichigan 48106
■
. C-7
1940
. R4
n-tym
'
Rohm an, I r v i n g ,
j
A s tu d y o f th e 'to p o g r a p h ic and m ic ro s c o p ic
a n a t o m y o f th e d u c t u s a r t e r i o s u s
w i t h ac o n s i d e r a t i o n
o f po t b l e f a c t o r s
in i t s
c lo s u re ...
New Y k c 1 9 4 0 ? 3
,'5 p .l.,1 7 6 t y p e w r i t t e n l e a / o s . i l l u s . ,
ta b le , d ia g rs .
2 9 c in .
T h e s i s ( i ' k . D . ) - New Y o r k u n i v e r s i t y ,
G ra d u ate s c h o o l, 1940.
B i b l i o g r a p h y • p,. 1 6 4 - 1 7 6 .
AGOG42
Xerox University M icrofilms,
Ann A rbor, Michigan 48106
T H IS D IS S E R TA TIO N HAS BEEN M IC R O F IL M E D E X A C T L Y AS REC EIVED.
A
stu d y
cf th e to p o g ra p h ic
and
m icro sco p ic a h ato h y
OF THE DUCTUS ARTERIOSUS
Y/ITH A COIISIDERAT ION OF POSSIBLE FACTORS
IK ITS CLOSURE
IRVING REULAN
Subm itted i n p a r t i a l f u l f u l l m e n t of tL e requ irem ents
f o r th e degree of d o c to r o f ph ilosop hy a t New York
U n iv e r s ity .
TABLE OF CONTENTS
I.
I n tr o d u c tio n
I I « L ite ra tu re
H is to ric a l
E x p e rim en ta l s tu d ie s
(a ) I n j e c t i o n e x p erim en ts
(b ) C a sts of th e d u c tu s
(c ) Models o f c i r c u l a t i o n
E n ib ry o lo g ical c o n s id e r a tio n s
C om parative anatom y
A natom ical c o n s id e r a tio n s
Course o f th e d u ctu s a r te r io s u s
A nom alies
P o s tn a ta l s tr u c tu r e o f th e ductus a r te r i o s u s
The p a te n t d u ctus a r t e r i o s u s
Time o f p o s tn a t a l c lo s u r e
M easurem ents
’’R id g e ", "v a lv e " o r f o ld o f th e ductus
C o n sid e ra tio n s o f th o v a rio u s d e s c r ip tio n s
and e x p la n a tio n s o f th e " rid g e " or " v a lv e " .
H is to lo g ic a l c o n s id e r a tio n s
I n t e r n a l b le e d in g
R o ta tio n , s h i f t i n g and to p o g ra p h ic changes
C om pression o f th e d u c tu s a r t e r i o s u s
T h e o rie s o f c lo s u re o f th e d u ctu s a r te r io s u s
(a ) Of h i s t o r i c a l i n t e r e s t
TABLE OF COMEKTS ( C o n t» d )
Pages
(b ) Thrombus fo rm a tio n in lumen
98
(0 ) Inflam m atory changes
98
(d ) S h i f t in topogi'aphy
98 - 100
(e ) C om pression - by l e f t b ro n ch u s, pulmonary
a rte ry , e tc .
100
( f ) E xpansion o f lung s
100 - 101
(g ) F a l l i n blood p re s s u re
101 - 104
(h ) V alve a c tio n and changes i n blood p re s s u re s
104 - 105
(1 ) M uscular c o n tr a c tio n
105 - 107
( j ) A c tiv e p r o l i f e r a t i o n , th ic k e n in g or
s h rin k in g
107 - 108
P o s tn a ta l c lo s u r e and o b l i t e r a t i o n
P h y s io lo g ic a l c o n s id e r a tio n s o f blood c i r c u l a t i o n
O nset o f r e s p i r a t i o n
III.
IV.
VII.
- 112
M a te r ia ls and m ethods
115 - 121
D e s c rip tio n and d is c u s s io n
122 - 148
H is to lo g ic a l c o n s id e r a tio n s
V I.
109
112 - 114
G ross anatom y
V.
108 - 109
122 - 139
(
139 - 148
C o n clu sio n s
149 - 160
Summary
161 - 163
B ib lio g ra p h y
164 - 176
INTRODUCTION
-
1-
T h is t h e s i s i s th e r e s u l t o f an in v e s t ig a ti o n o f th e d u c tu s a r t e r i o ­
su s and was u n d e rta k e n a t th e s u g g e s tio n o f P ro fe s s o r G ustave Joseph
Noback t o wham I w ish t o e x p re s s my th a n k s f o r h is s in c e re g u id an ce
in v a lu a b le a i d
and
d u rin g th e p ro g re s s o f th e s tu d y .
The to p o g rap h y o f th e d uctu s a r t e r i o s u s , th e lo c a tio n o f i t s e n ­
tr a n c e i n t o th e a o r ta and th e p re sen c e o f a "v a lv e o f th e d u ctu s
a r t e r i o s u s " i n th e f u l l t e r n newborn i n f a n t , have shown t h a t th e d e s­
c r i p t i o n s a s re c o rd e d i n th e l i t e r a t u r e a re n o t in acco rd an ce w ith o u r
f in d i n g s .
The
th e o r ie s w hich o f f e r t o e x p la in th e change from p r e n a ta l
to p o s tn a ta l c i r c u l a t i o n have b een , i n th e l i g h t o f th e s e
b ased upon i n c o r r e c t and in a d e q u a te m o rp h o lo g ica l d a ta .
f in d i n g s ,
The pu rp o se o f
t h i s s tu d y was f u r t h e r t o in v e s t i g a t e th e g ro ss and m icro so o p io c h a r ­
a c t e r o f c e r t a i n s t r u c t u r e s i n th e p r e n a ta l, n e o n a ta l and p o s tn a t a l
p e r io d s .
T h is was done w ith th e hope t h a t more a c c u ra te o b s e rv a tio n s on
a la r g e r amount o f m a te r ia l would le a d t o a c l e a r e r under s ta n d in g o f th e
anatomy in v o lv e d .
A b a s i s i s th u s e s ta b lis h e d f o r a b e t t e r a tte m p t a t
an e x p la n a tio n o f th e meohanisms le a d in g to th e p h y s io lo g ic a l c lo s u r e
and a n a to m ic a l o b l i t e r a t i o n o f th e d u ctu s a r t e r i o s u s w hich i s a s s o c ia te d
w ith th e e s ta b lis h m e n t o f r e s p i r a t i o n .
S e v e ra l th e o r ie s w hich a tte m p t t o e x p la in th e c lo su re end th e ob­
l i t e r a t i o n o f th e d u ctu s a r t e r i o s u s have been p u t f o r t h .
These t h e o r i e s
a r e based m ain ly upon th e s tu d ie s c a r r ie d o u t upon th e to p o g rap h y o f th e
th o r a c ic s t r u c t u r e s o f th e newborn.
Since th e r e a re many c o n f l i c t i n g
d e s c r ip tio n s o f th e c o u rse and to p o g ra p h ic r e l a t i o n s o f th e d u ctu s a r ­
t e r i o s u s , a s tu d y was made in o rd e r t o d eterm ine more a c c u r a te ly th e
e x a c t r e l a t i o n s h i p s o f th e a d ja c e n t s tr u c tu r e s by d is s e o tio n o f th e
f e t u s , newborn and i n f a n t .
These were re c o rd e d by means o f o rth o s c o p ic
-2 -
d raw in g s, p h o to g rap h s and o a s ts o f th e s u c c e ssiv e s ta g e s o f th e d i s s e c t ­
ions*
The te c h n iq u e employed was d e sig n e d t o m inim ize a s f a r a s p o s s ib le
e r r o r s due t o th e p e rs o n a l elem ent*
The l i t e r a t u r e was th o ro u g h ly examined and t h e f u r t h e r f in d in g s in
t h i s la b o r a to r y recorded*
The v e r te b r a l l e v e l s o f th e d u o tu s a r t e r i o s u s
and th e su rro u n d in g s t r u c t u r e s w ere c a r e f u l l y determ ined and th e p ro ­
g re s s iv e changes o o o u rrin g w ith in c re a s e i n o h ro n o lo g ic a l age and d eg ree
o f developm ent w ere noted*
F in d in g s re g a rd in g th e c h a r a c te r o f th e e n ­
tr a n c e o f th e duotus i n t o th e a o r ta made i t n e c e s sa ry t o more c a r e f u l l y
reexam ine and t o re c o rd more p r e c i s e l y i t s r e l a t i o n to n e ig h b o rin g
s tr u c tu r e s an d t o map out th e e x a o t a r e a s o f c o n ta o t betw een i t and th e
c o n tig u o u s s t r u c t u r e s .
R e c o g n itio n o f th e s e a re a s o f c o n ta c t i s e s s e n t i a l
in a r r i v i n g a t a b e t t e r u n d e rs ta n d in g o f th e r e l a t i v e p re s s u re s e x e rte d
upon th e d u o tu s by th e su rro u n d in g s t r u c t u r e s d u rin g f e t a l , newborn and
p o s tn a ta l l i f e *
An a tte m p t t o e v a lu a te th e p ro b ab le r o le s o f th e s e
p re s s u re s i n th e p ro c e ss o f p h y s io lo g ic a l c lo s u re and a n a to m ic a l o b l i t e r ­
a t i o n i s m ade.
An e x p la n a tio n o f th e p h y s io lo g ic a l c lo s u re o f th e d u o tu s
a r t e r i o s u s u t i l i z i n g th e com pressing fo rc e s w hich r e s u l t from a co m p eti­
t i o n f o r space among th e th o r a c io v is c e r a i s o ffe re d * .
A c r i t i c a l ex am in atio n o f th e l i t e r a t u r e was made t o d eterm ine
w hether any a tte m p t had e v e r been made to c o r r e l a t e th e p re s s u re s o f
a d ja c e n t o rg an s w ith th e p e c u li a r c h a r a c t e r i s t i c s o f th e m orphology o f
th e ductus a r t e r i o s u s a s re c o rd ed by us*
The " v a lv e o f th e d u c tu s a r t e r i o s u s ” , was found t o be p re s e n t i n
e v e ry c a s e , e x c e p t tw o, and i t v a r ie d from a s in g le rid g e o f g r e a t
h e ig h t t o s e v e r a l c o n tig u o u s r id g e s o f l e s s e r h e ig h t*
-3 -
The v a r ia tio n s i n s i z e , number and ty p e o f r id g e s were s tu d ie d and
th e freq u en cy w ith w hich th e y w ere found b o th m a o ro sc o p ic a lly o r
m ic ro s c o p ic a lly d e te rm in e d .
I t s e x a c t p o s itio n r e l a t i v e t o th e o r ig i n
and te rm in a tio n o f th e duotus was o b serv ed in o rd e r to a s c e r t a i n i t s
p ro b a b le r o le i n th e re d u c tio n o f th e lumen o f th e duotus*
M easure­
m ents o f th e s iz e o f th e v a lv e were made and compared w ith th e s i z e o f
lumen o f th e d u c tu s d u rin g th e v a rio u s s ta g e s o f developm ent in an
e f f o r t t o d e term in e th e f u n c tio n o f th e v a lv e .
A c o r r e l a t i o n betw een
th e s iz e o f th e " v a lv e ” and th e l e v e l of e n tra n c e o f th e d u ctu s i n t o
th e a o r ta was made in o rd e r t o determ ine w hether th e v a lv e m ight i n ­
flu e n c e th e c o u rse o f th e d u c tu s .
A h i s t o l o g i c a l stu d y o f th e e n t i r e duotus a r t e r i o s u s was o a r r ie d
o u t in th e f e t u s , newborn and young i n f a n t .
T his p o r tio n o f th e stu d y
a tte m p te d t o determ in e th e h i s t o l o g i c a l c h a r a c t e r i s t i c s o f th e w a ll o f
th e duotus a r t e r i o s u s w ith s p e c ia l em phasis on th e a re a s o f c o n ta c t w ith
a d ja c e n t s t r u c t u r e s .
An i n t e r p r e t a t i o n o f th e s e p e o u lia r h i s t o l o g i c a l
c h a r a c t e r i s t i c s i n s p e o if ic p o r tio n s o f th e d u ctu s a r t e r i o s u s a s r e s u l t ­
in g from g r e a t e r s tim u la tio n , lo c a l iz e d p re s s u re s o r o th e r f a c t o r s i s
advanced.
The m a te r ia l a v a ila b le was s tu d ie d in o rd e r t o o b ta in in fo rm a tio n
re g a rd in g th e s t r u c t u r e , fre q u e n c y , and tim e o f app earan ce o f th e v a lv e ;
and i t s h i s t o l o g i c a l d i f f e r e n t i a t i o n was compared w ith t h a t o f th e
d uctus a s a whole i n an e f f o r t t o d e term in e w h eth er suoh f a c t o r s a s
p re s s u re on th e l e f t b ro n c h u s, d ia m e ter o f th e d u c tu s, o r th e s iz e
o f th e a o r t i c o r i f i c e o f th e d u c tu s m ig h t have an in flu e n c e on th e
-
4-
c h a r a o te r o f th e "-valve o f t h e d u o tu s a r t e r i o s u s . "
The f in d in g t h a t t h e e n tra n c e o f t h e d u ctu s in to th e a o r ta -was
in to th e p ro x im al p a r t o f t h e th o r a c ic a o r t a , i n s te a d o f in to th e
d i s t a l p a r t o f th e a ro h o f t h e a o r t a , le d t o in v e s t ig a ti o n o f th e
le v e l and m anner o f e n tra n c e o f th e d u ctu s i n t o th e a o r t a .
The s h i f t ­
in g o f th e d u c tu s in th e f e t u s and newborn d u rin g grow th r e s u lte d in
a d d itio n a l f a c t o r s to be c o n sid e re d i n th e u n d e rs ta n d in g o f th e c lo s u re
o f th e d u o tu s .
The stu d y j u s t m entioned d is c lo s e d th e p resen ce o f a
deep l a t e r a l groove i n th e w a ll o f th e d u c tu s a r t e r i o s u s a t i t s o b liq u e
e n tra n c e i n t o th e th o r a c ic a o r t a .
T h is fin d in g m ust a ls o be c o n sid e re d
in an a tte m p t t o u n d e rs ta n d th e change from th e p r e n a ta l t o th e p o s t­
n a ta l ty p e o f b lo o d c i r c u l a t i o n .
The to p o g ra p h io anatom y and r e l a t i o n s o f th e th o r a c ic s tr u c tu r e s to
th e d uctus a r t e r i o s u s a r e th e r e f o r e re d e s c rib e d and a h is t o l o g i c a l s tu d y
has been made o f th e component p a r t s o f th e d u ctu s a r t e r i o s u s .
M easure­
m ents have been made and c o r r e la ti o n s a tte m p te d in o rd e r t o e v a lu a te
th e f a c to r s in v o lv e d i n an e x p la n a tio n o f th e p h y s io lo g ic a l c lo s u re and
a n a to m ic a l o b l i t e r a t i o n o f th e d u o tu s a r t e r i o s u s .
LITERATURE
-5 IIIS10RICAL
Ivlany s tu d ie s upon th e d u ctus a r t e r i o s u s have been made b u t a
s a t i s f a c t o r y comprehensive d is c u s s io n o f th e r e p o r t s o f previous
w orkers i s n o t a v a i l a b l e .
H ost o f th e s e s t u d i e s have been concerned
c h i e f l y w ith th e p hy sio log y o f th e blood c i r c u l a t i o n and th e c lo s u r e
of th e d u c tu s .
Few have s tu d ie d th e anatomy, b o th g ro s s and m ic ro ­
s c o p ic , and th e topography of th e a d j a c e n t s t r u c t u r e s and t h e i r r o lo s
in th e c lo s u r e o f th e ductus and i n th e changing of blood flo w .
As a
r e s u l t of th e s e e a r l i e r s t u d i e s many t h e o r i e s liave been fo rm u la te d , bu t
in th e l i g h t o f our f in d i n g s th e s e t h e o r i e s a r e based upon i n c o r r e c t
o b se rv a tio n s o r on in a d eq u a te m a t e r i a l ; and i n s e v e r a l s tu d ie s th e te c h ­
niques employed a r e open t o q u e s t i o n .
Knowledge of th e e x i s t e n c e o f th e d u ctu s a r t e r i o s u s may be tr a c e d
back to Galen (as quoted i n D alton (1 88 4 )) who f i r s t d e sc rib e d i t .
The
fo llo w in g t r a n s l a t i o n of Galen, is taken from D a lto n - "For a s long a s th e
lung has only to be n o u ris h e d and grown, i t i s s u p p lie d simply w ith blood;
b u t when i t i s ready t o ta k e on an a c t i v e m o tio n , i t s t i s s u e s become l i g h t ­
e r and capablo of ex pansion and com pression by t h e movements o f the c h o s t .
On t h a t a cco un t th e vena c av a, i n th e f e t u s , communicates by an opening
(foramen ov ale) w ith th e a r t e r i a v e n a l i s (pulm onary v e i n ) .
As t h i s
l a t t e r v e s s e l th u s perform s f o r t h e lung th e o f f i c e o f a v e in ( t h a t i s ,
s u p p lie s i t w ith blo o d f o r i t s n o u ris h m e n t), i t s companion (th e p u l­
monary a r t e r y ) must needs a t t h i s tim e serve th e purpose o f an a r t e r y ,
and i t i s c o n se q u e n tly made t o communicate w ith th e a o r t a .
As th e s e
two v e s s e ls (pulmonary a r t e r y and a o r t a ) a r e s i t u a t e d a l i t t l e d is ta n c e
a p a r t , t h e i r communication i s e f f e c t e d by means o f a t h i r d s m a lle r one
-6 -
( d u ctu s a r t e r i o s u s ) , w hich f o m s a ju n c tio n w ith e a c h ." . . . "For soon
a f t e r b i r t h , e i t h e r w ith in a day o r tw o, o r i n some a n im a ls, a f t e r fo u r
o r f iv e days o r a l i t t l e lo n g e r , you w i l l f i n d th e membrane a t th e
foram en (o v a le ) c o a le s c in g , b u t n o t y e t f u l l y a d h e r e n t." . . . " In lik e
manner th e c o n n ec tin g v e s s e l (d u o tu s a r t e r i o s u s ) betw een th e a o r ta and
th e vena a r t e r i a l i s , w h ile a l l o th e r p a r t s o f th e body in c re a s e in s iz e ,
n o t o n ly s to p s growing b u t a c t u a l l y d im in is h e s , becoming a f t e r a tim e
c o m p le tely s h r iv e lle d and s o l i d i f e d . "
No re fe re n c e t o th e d u o tu s a r t e r i o s u s a p p e a rs in m ed iev al l i t e r a t u r e
and i t seems t o have p assed unnoted u n t i l i t was a g a in d e sc rib e d by
B o ta lli (1565) in h is m onograph, "Vena a r te r iu m n u t r i x , a n u lla a n te a
n o t a t a ," in th e s e c tio n d e a lin g w ith h is a n a ta m io a l o b s e r v a tio n s .
He
was in te r e s t e d in th e p e r s i s t e n t foram en o v ale b u t su b seq u en t w o rk ers,
a p p lie d h is name t o th e d u o tu s a r t e r i o s u s , i . e . , d u o tu s a r t e r i o s u s
B o t a l l i o r B o ta l's Duot.
V e s a liu s (1541) a p p a r e n tly was unaware o f th e d uotus a r t e r i o s u s f o r
he makes no m ention o f i t in h is "De Humani C o rp o ris F a b rio a ."
Harvey
(1628) however used th e d uotus in h is e x p la n a tio n o f th e f e t a l ty p e o f
c irc u la tio n .
"A nother u n io n i s t h a t by th e vena a r t e r i o s a , o r pulmonary
a r t e r y , and i s e f f e c te d when t h a t v e s s e l d iv id e s i n t o two branches a f t e r
i t s escape from th e r i g h t v e n t r i c l e o f th e h e a r t .
I t i s a s i f t o th e two
tru n k s a lre a d y m entioned a t h i r d were su p erad d ed , a k in d o f a r t e r i a l
c a n a l, c a r r ie d o b liq u e ly from th e vena a r t e r i o s a , o r pulm onary a r t e r y to
p e r f o r a te o r te rm in a te in th e a r t e r i a magna o r a o r t a .
In th e embryo,
c o n se q u e n tly , th e r e a r e , a s i t w ere, two a o r t a s , o r two ro o ts o f th e
a r t e r i a magna, s p rin g in g from th e h e a r t .
T h is c a n a lis a r t e r i o s u s s h rin k s
g ra d u a lly a f t e r b i r t h , and i s a t le n g th and f i n a l l y a lm o st e n t i r e l y
w ith e re d , and removed, l i k e th e u m b ilic a l v e s s e l s ."
The p a te n c y o f th e d u otus f o r some tim e a f t e r b i r t h was a ls o known
t o H arvey.
"But we f u r t h e r o b s e rv e , t h a t th e p a ssa g es i n q u e s tio n a re
n o t o n ly p e rv io u s up t o th e p e rio d o f b i r t h in man, a s w e ll a s in o th e r
a n im a ls, a s a n a to m ists in g e n e ra l have d e sc rib e d them ; b u t f o r s e v e ra l
months su b se q u e n tly , i n seme in d e ed f o r s e v e r a l y e a r s , n o t t o say f o r
th e whole co u rse o f l i f e j a s f o r exam ple, in th e g o o se, s n ip e , and
v a rio u s b i r d s , and many o f th e s m a lle r a n im a ls .
And t h i s circu m stan ce
i t w as, p e rh a p s, t h a t imposed upon B o ta llu s , who th o u g h t he had d i s ­
covered a new passage f o r th e b lo o d from th e vena cava in to th e l e f t
v e n t r i c l e o f tine h e a r t • • • • in human em bryos, and in th e embryos o f
anim als in whioh th e com m unications a re n o t d o s e d , th e same th in g hap­
pen s, namely*, t h a t th e h e a r t by i t s m otion p ro p e ls th e blood by obvious
and open p assag es from th e vena cava in to th e a o r ta th ro u g h th e c a v i t i e s
o f b o th v e n t r i o l e s ; th e r i g h t one r e c e iv in g th e b lo o d from th e a u r i c l e
and p r o p e llin g i t by th e vena a r t e r i o s a , o r pulm onary a r t e r y , and i t s
c o n tin u a tio n , named th e duotus a r t e r i o s u s , in to th e a o r t a . "
The duotus a r t e r i o s u s was a l s o known t o s e v e r a l o th e r a n a to m ists
o f th e s e v e n te e n th and e ig h te e n th c e n tu r i e s , b u t th e y w ere p rim a rily
i n t e r e s t e d in th e co u rse o f blo o d flow and th e r e f o r e re g a rd ed i t a s
m erely a c o n n ectin g passage o a rry in g blood*
n e c tio n w ith changes in c ir c u la t io n *
O thers m en tio n i t in con­
Diagrams o r schem ata o f c i r c u l a ­
t i o n a r e t o be found in th e a n ato m ies o f o ld e r w r i t e r s b u t no m en tio n
o f th e duotus a r t e r i o s u s i s made i n th eir te x ts *
The fo llo w in g p la te s
oopied from th e t e x t s o f F a b r ic iu s (1 5 8 7 ), B a r th o lin (1665) and H orner
(1 8 5 1 ), i l l u s t r a t e t h i s , p o i n t .
F ig . 1 . F a b rio iu s
"C" (D uctus A r te r io s u s )
F ig . 2 . B a r th o lin
" e -e "
F i g . 2A. H orner
"6"
V ario u s fu n c tio n s have been a s s ig n e d t o th e d u o tu s by d i f f e r e n t
in v e s t i g a t o r s .
Of h i s t o r i c a l i n t e r e s t i s th e th e o ry o f G alen who b e­
lie v e d t h a t i t a s s u re d th e a o r ta a su p p ly o f "Pneuma" from th e lu n g s .
Harvey (1628) c o r r e o tly e x p la in e d i t s f u n e tio n when he s t a t e d t h a t
when th e h e a r t c o n tr a c ts th e blood i s r e g u la r ly p ro p e lle d by th e c a n a l
o r passage from th e r i g h t v e n t r i c l e i n t o th e a o r t a .
P e a sle e (1854)
d e sc rib e d th e d u ctu s a s a "w aste p ip e " t h a t co n d u cts away th e ex cess
o f blo o d n o t u sed by th e lu n g s .
R oeder ( ’02) d e s c rib e d th e r o l e o f
th e duotus d u rin g developm ent - a t b i r t h and a f t e r b i r t h - a s an
e q u a liz e r o f th e h ig h e r p re s s u re and p u l l on th e a o r t i o a rc h a s w e ll
a s a means o f e q u a liz in g m arked p re s s u re f lu c tu a ti o n s i n th e a o r t a and
pulmonary a r t e r y .
The v e s s e l a ls o c a u se s a r e v e r s a l o f th e f e t a l blood
p r e s s u r e , th e fo rm atio n o f a new p h y s io lo g ic a l blo o d p re s s u re d if f e r e n c e ,
and f i n a l l y b rin g s ab o u t th e d e f i n i t e s e p a r a tio n o f b o th stream s o f flo w .
Needham (1667) d e s c rib e s th e d u c tu s and s t a t e s t h a t th e pulmonary
end i s w id e r th a n th e a o r t i c end and th e r e f o r e can one e a s i l y t e l l th e
I
-
d i r e o t i o n o f th e b lo o d flow*
9-
The p h y sio lo g y o f t h e b lo o d flo w h o ld
more i n t e r e s t f o r th e s e w orkers th a n t h e anatom y and t h i s i s r e f l e c t e d
i n m ost o f t h e i r w ork.
The anatomy o f th e duotus a r t e r i o s u s was con­
s id e r e d a s o f secondary im portance and th e r e f o r e re c e iv e d b u t l i t t l e
a t t e n t i o n ; th e g r e a te r em phasis b e in g p la o e d e i t h e r upon th e p h y sio lo g y
o f b lo o d c i r c u l a t i o n o r th e c lo s u r e o f th e d u c tu s a r t e r i o s u s and i t s
e f f e c t upon changing th e f e t a l ty p e o f c ir c u la t io n *
The p h y s io lo g ic a l
s tu d ie s r e s u l t e d i n th e fo rm u la tio n o f many t h e o r i e s .
In m ost o ases
th e s e th e o r ie s a r e o f h i s t o r i c a l v a lu e o n ly s in c e th e y w ere b a se d upon
a v e ry s l i g h t knowledge o f th e anatom y in v o lv e d o r upon in a d e q u a te
m a te r ia l*
EXPERIMENTAL STUDIES
Many o f th e s tu d ie s d e a lin g w ith th e d u ctu s a r t e r i o s u s w ere c a r r i e d
o u t s o le ly by means o f d is s e c tio n o f c ad a v e r m a te ria l*
The d e d u c tio n s
werel made on th e b a s is o f th e s e v i s u a l o b s e r v a tio n s and th e th e o r ie s
th e n propounded.
Very few e x p erim en ts have b een perform ed on l iv in g
an im als*
H a lle r (1780) was one o f th e e a r l i e s t w o rk ers t o a p p ly p h y s io lo ­
g ic a l m ethods t o th e s tu d y o f c i r c u l a t i o n .
He found t h a t a n in c re a s e d
blo o d flow frcm th e d u ctu s a r t e r i o s u s in to th e a o r ta r e s u l t e d when th e
u m b ilic a l v e s s e ls were t i e d o f f .
He a l s o o b serv ed t h a t t h i s le d t o an
in o re a s e d blood flow t o th e lungs*
K ilia n (1826) a tte m p te d i n j e c t i o n ex p erim en ts w ith v a r io u s c o lo re d
m a te ria ls .
Red and b lu e m asses w ere i n j e c t e d i n t o th e pulm onary a r t e r y
and a o r t a o f f e tu s e s s im u lta n e o u s ly .
He o b serv ed t h a t th e c e r e b r a l
p o r tio n o f th e a o r ta was f i l l e d w ith a m ix tu re w hich was g re e n e r th a n
t h a t i n th e abdom inal a o r t i c p o rtio n *
o f re d d e r o o lo r*
The l a t t e r he found t o be
He assumed t h a t same o f th e c o lo r in g m a tte r fo m in g
*
-1 0 -
th e g re e n was mixed w ith th e red#
The r e s u l t s he o b ta in e d w ere p ro b a b ly
due t o unequal p re s s u re s w h ile i n j e c t i n g th e m a te r ia l#
A d e f i n i t e in c re a s e in i n t e r e s t in th e duotus was shown d u rin g th e
l a t t e r p a r t o f th e n in e te e n th c e n tu ry and t h i s r e s u lt e d in muoh e x p e r i­
m en tal w ork.
Schanz (1889) a tte m p te d t o prove t h a t th e c lo s u r e o f th e
d u ctu s r e s u lte d from a p u llin g o r t e a r i n g fo rc e e x e r te d upon i t by th e
pericard iu m #
He s tu d ie d th e p o s itio n o f th e th o r a c ic v is c e r a in a s ix
m onths' o ld f e tu s and th e n i n f l a t e d th e lu n g s#
He f a i l e d however to
ta k e in to c o n s id e ra tio n th e p a t t e r n o f e x p a n sio n o f th e lu n g s , assum ing
t h a t th e y were u n ifo rm ly i n f l a t e d s im ila r t o a b a llo o n #
lie a l s o o u t
windows in th e th o r a c ic w a ll o f s t i l l b o r n o h ild r e n and ob serv ed th e
s h i f t i n p o s itio n o f th e th o r a c ic v is c e r a r e s u l t i n g from th e a r t i f i c i a l
downward d isp la ce m e n t o f th e l i v e r and t h e r e s u l t a n t t r a c t i o n o f th e
p e ric a rd iu m upon th e th o r a c ic s tr u c tu r e s and d u c tu s .
Strassm ann (1894) c a r r ie d o u t a s e r i e s o f e x p erim en ts on f e t a l
and newborn dogs and c a t s .
He in je c te d a g e l a t i n s o lu tio n i n t o th e
ju g u la r v e in o f s t i l l b o r n newborns a t a p re s s u re o f 40 mm Iig. and a
p l a s t e r m ix tu re i n t o th e c a r o tid a r t e r y a t a p re s s u re o f 100 mm Hg,
Upon d is s e c tio n g e l a t i n was found i n th e pulm onary a r t e r y and d u ctu s
a r t e r i o s u s b u t no p l a s t e r had e n te re d t h e duotus#
From th e s e f i n d ­
in g s Strassm ann concluded t h a t a s a r e s u l t o f changes o c c u rrin g a t
b i r t h th e blood p re s s u re was r a is e d in th e a o r ta and lovrered in th e
pulm onary a r t e r y ; th e v alv e a t th e a o r t i c e n tra n c e t h e r e f o r e b ein g
com pressed a g a in s t th e a o r t i c opening o f t h e ductus an d th u s c lo s in g
o f f th e opening,
lie a ls o a tte m p te d to i n j e c t th e d u ctu s from th e
a o r ta in a 12-15 day o ld dog, b u t was u n s u c c e s s f u l.
H am ilto n , Woodbury
-1 1 -
and woods (*37) show t h a t i n th e dog a v a lv e e x i s t s a t th e a o r t i o open­
in g o f t h e duotus and t h i s c o n d itio n i n t h i s a n im al may p o s s ib ly have
g iv e n r i s e t o S trassm ann’ s d e s c r ip ti o n o f such a v a lv e a t t h a t l o c a t io n
i n man.
Strassm ann a ls o found t h a t he was s t i l l a b le t o i n j e c t th e
du otus from th e pulm onary end in specim ens o ld e r th a n sev en days a J fte r
b irth .
He th u s proved t h a t S c h a n z's fin d in g d w ere i n c o r r e c t .
Strassm ann
a l s o found t h a t th e i n j e c t i o n mass co u ld s t i l l be fo rc e d from t h e a o r t a
i n t o th e ductus a f t e r e ig h t d a y s.
As a r e s u l t o f th e s e i n j e c t i o n ex­
p e rim e n ts he assum es t h a t an in v e rs io n o f th e w a ll o f th e d u c tu s o ccu rs
and in c r e a s e s th e v a lv e - lik e a o tio n a t th e a o r t i o e n d . ( F ig . 3, No* I I
and IV ).
• Fifr *»•
—
..
(i.
Ap .
Ao.
|
«
Z u letzt set n u n uoch iibor den folgonden V ersuch boricM et,
do r ein p o sitiv es K o su lta t orpeben h a t:
F ig . 3 . Strassm ann
" D .a ." Ductus A r te r io s u s
E xperim ents t o d em onstrate th e manner i n w hioh a p e r s i s t e n t p a te n t d u ctu s
a r t e r i o s u s may occur were a l s o c a r r ie d o u t b y S trassm ann by means o f
in c r e a s in g th e i n j e c t i o n p r e s s u r e s .
m ents u sed p la n tig ra d e a n im a ls .
S trassm ann i n h i s i n j e c t i o n e x p e r i­
Because o f t h e i r h o r iz o n ta l p o s itio n
th e to p o g rap h y o f th e v is c e r a d i f f e r s from t h a t o f m an.
Of h is f i f t e e n
-1 2 e x p erim en ts (11 on dogs and 4 on human new borns) o n ly s i x w ere s u c c e ss ­
fu l •
When th e in j e c t i o n was made i n to th e c a r o t i d a r t e r y o r l e f t
v e n t r i c l e none o f th e in je o tio n mass was found i n th e d u o tu s a r te r io s u s #
Of th e s i x s u c c e s s fu l in je c tio n s o n ly one was made in a human i n f a n t
t h a t had n o t b re a th e d , th e o th e r f i v e i n je o tio n s were in to i n f a n t s t h a t
were s e v e r a l days o ld and in w hich c lo s u r e h as a lr e a d y begun*
Haberda (1896) o r i t i o a l l y review ed th e work o f Strassm ann and
Schanz*
He re p e a te d t h e i r experim en ts and found no change i n th e
p o s itio n o f th e th o r a c ic v is c e r a on i n f l a t i n g th e lungs*
He a ls o a t ­
tem pted i n j e c t i o n experim ents on fo u r newborns and a one-day o ld o h ild *
He c r i t i c i z e d th e p re s s u re s used by Strassm ann a s p ro b a b ly n o t b ein g
s im ila r t o th o s e in th e newborn.
P h y s io lo g ic a l s tu d ie s w ere a ls o
c a r r ie d o u t by Zuntz and C ohnstein (1884) who worked w ith sh eep , d o g s,
p ig s and r a b b i t s and t h e i r r e s u l t s were assum ed to a p p ly a s w e ll t o
humans,
Haberda th e r e f o r e in je c te d a mass o f b lu e g e l a t i n i n t o th e
r i g h t s u b c la v ia n a r t e r y under a low er p re s s u re and found t h a t th e g e l a t i n
had f i l l e d th e a o r ta , ductus and pulmonary a r te r y *
S o h arfe (1900) a ls o perform ed i n f l a t i n g e x p erim en ts and found t h a t
• J l f i l l i n g th e lungs w ith a i r " d id n o t r e s u l t in a s h i f t in p o s it io n o f
th e th o r a c ic v i s c e r a .
Z iegenspeok (1902-10) experim ented w ith a l a r g e r s e r i e s o f a n im a ls
th a n d id th e p re v io u s i n v e s t i g a t o r s .
He worked on se v e n te e n p ig f e t u s e s ,
f iv e human and seven sheep fe tu s e s and f o r t y embryos w hich were in je c te d
w ith c o lo re d g e l a t i n by means o f th e u m b ilic a l v e in s , and th e n hardened
in a lc o h o l*
These were th e n exam ined, m easurem ents b e in g made on th e
f e tu s e s w hich ranged from 13 cm. t o 54 cm. i n le n g th *
R oeder ( '0 2 ) re p e a te d th e ex perim ents o f Strassm ann on th e cad av er
-1 3 -
o f a newborn t o determ ine th e p re s s u re t h a t th e d u o tu s was a b le t o
w ith s ta n d .
He found t h a t a p re s s u re o f 90 mm Hg. produoed an aneurysm
i n th e d u otus and t h i s aneurysm d id n o t d is a p p e a r when th e p re s s u re was
low ered t o 45-50 mm Hg.
A t 120-140 mm Hg. p re s s u re s tr e tc h i n g o f th e
d u o tu s o c c u rre d le a d in g t o te a r in g o f th e in n e r w a l l .
p re s s u re r u p tu r e o f th e d u ctu s o c c u rre d .
a p r e d i l e c t i o n f o r aneurysm fo rm a tio n .
A t 150 mm Hg.
He assum es t h a t t h e d u ctu s has
In th e l i g h t o f h is f i n d i n g s , i t
a p p e a rs t h a t th e i n j e c t i o n p re s s u re s employed by th e p re v io u s in v e s tig a ­
t o r s were to o g r e a t t o r e p r e s e n t p h y s io lo g ic a l c o n d itio n s .
K ir s te in ( ’ 10) a ls o o a r r ie d o u t a s e r i e s o f i n j e c t i o n e x p erim en ts
w ith w a te r and o b ta in e d r e s u l t s t h a t w ere i n o p p o s itio n t o th o s e o f
S trassm an n .
K ir s te in u sed fe tu s e s and in f a n ts ra n g in g from n in e f e t a l
m onths to e i g h t days p o s t n a t a l .
W ater was used b ecau se i t i s n o t s p e c i­
f i c a l l y h e a v ie r th a n p l a s t e r o f p a r i s p a s te and i s c lo s e r t o th e s p e o if io
g r a v i t y o f b lo o d .
A sm all window was o u t i n th e th o ra c io w a l l , th e thymus
r a i s e d , b o th la y e r s o f p le u ra pushed a s id e and th e p e ric a rd iu m a t th e
r o o t o f th e g r e a t v e s s e ls exposed.
A s l i t was made i n th e p e rio a rd iu m
and an i n j e c t i o n n e e d le in s e r te d i n t o th e pulm onary a r t e r y above i t s o r ig i n
to serv e a s a n open c a n n u la .
An i n c i s i o n was made i n th e t i p o f th e f in g e r
t o a c t a s a n in d ic a to r and th e i n j e c t i o n was made in to th e r i g h t c a r o ti d
a rte ry .
V ery s h o r tly a f t e r th e i n j e c t i o n was begun w a te r flow ed ou t o f
th e n e ed le i n th e pulmonary a r t e r y and a l s o th e i n c is e d f i n g e r t i p .
T h is
dem onstrated th e p o s s i b i l i t y o f a r e v e rs e flo w from th e r i g h t c a r o ti d
a r t e r y in to th e a o r ta and th e n in to th e d u ctu s a r t e r i o s u s an d pulmonary
a rte ry .
These fin d in g s o f K ir s te in r e f u t e th e p o s s i b i l i t y o f a v a lv e o f
S trassm ann ly in g a t th e ju n c tio n o f th e d u c tu s and a o r t a . (S ee F ig . 3,
No. I I ) .
-1 4 S tie n o n ( ’ IE ) c a r r ie d o u t a s e r i e s o f e x p erim en ts in an a tte m p t to
v e r i f y S trassm an n ’ s f in d i n g s .
from below upw ards.
He in je c te d in to th e d escen d in g a o r ta
The i n j e c t i o n m a te r ia l p a sse d in to th e d u c tu s
a r t e r i o s u s and in to th e isth m u s o f th e a o r ta s im u lta n e o u s ly , th u s
d e m o n stra tin g th e absence o f a v alv e a s p o s tu la te d by Strassm ann#
On
in j e o t i n g from above downward he found t h a t th e mass d is te n d e d th e
isthm us o f th e a o r ta and d e p re ssed th e duotus a r t e r i o s u s th u s o c clu d in g
i t s lumen#
L inzenm eier ( ’ 14) i n f l a t e d th e lungs t o d eterm in e th e e f f e c t o f th e
ex p an sio n o f th e lu n g s upon th e duotus a r t e r i o s u s #
A s h i f t in th e po­
s i t i o n o f th o r a c ic s tr u c tu r e s was o b ta in e d i n e v ery o ase c o n tra ry t o th e
fin d in g s o f S c h a rfe .
A s e r i e s o f p a r a f f in c a s ts o f th e i n t e r i o r o f th e
ductus was a ls o made o f fiv e f e tu s e s , th r e e p rem atu res and two newborns
t h a t had n o t b r e a th e d .
S trassm an n .
He found no v a lv e such a s was p o s tu la te d by
The c a s t o f N o .l newborn w eighing 2560 gm# showed a v e ry
s l i g h t im p ressio n on th e concave sid e which he s t a t e s co u ld n o t le a d t o
a n a rro w in g .
In t h i s case th e in je o tio n p re s s u re was
so g r e a t a s t o r e s u l t
in a s tr e to h in g o r expan sio n o f th e d u ctu s a r t e r i o s u s and c o n se q u e n tly
Fig. 5.
K
I
P i n f l u u i i l a lt Drakknick.
1 Anriofct vo. von. II Analcht vo. Uatra. Ill Ausiebt von nnten and MnUn.
* w Aw tm w tlaa dM Daotn. artuioou. f = Folaoanloatlam do* Dnotni mrUrioMi.
K — KnickitoUe.
Figo 4 .
L inzenm eier
-1 5 -
any e f f e c t o f a change in p o s itio n was n o t n o tic e a b le *
In newborn
No* 2 , 53 om* cro w n -h eel le n g th , a sm all rid g e was found on th e concave
s id e o f th e d u c tu s , e l l i p t i c a l i n sh a p e , and a t a s h a rp a n g le t o th e
d u o tu s , and th e r e f o r e he concluded from t h i s t h a t t h e d u ctu s was tu rn e d
on i t s lo n g a x is and a p in o h in g o r k in k in g had r e s u lte d *
No* 3 , 49 cm* cro w n -h eel le n g th , was u n s a tis f a c to r y *
53 cm* newborn was s im ila r t o No* 2*
s im ila r t o No* 2 and No* 4*
The c a se o f
C a st No* 4 , o f a
No* 5 was 44 cm* and No* 6 was
He a ls o made c a s t s o f th r e e o th e rs *
They
w ere shaped l i k e an h o u r- g la s s - a c o n s t r i c t i o n i n th e m iddle and th e
ends t h i c k e r and e l l i p t i c a l *
G raper ( ’21) c a r r ie d o u t some i n j e c t i o n ex p erim en ts and h is fin d in g s
a l s o c o n tr a d ic te d th o s e o f Strassm ann*
He found t h a t i t i s p o s s ib le t o
show a v a lv e fo rm a tio n a t th e a o r t i c end o f th e d u c tu s b y f i l l i n g i t w ith
p l a s t e r u n d e r a s tro n g p re ssu re *
e r r o r i n te c h n iq u e *
c o lo re d w ater*
S trassm ann b ased h is th e o ry on t h i s
G raper a ls o c a r r i e d o u t e x p erim en ts w ith c l e a r and
The a o r ta and pulmonary a r t e r y w ere uncovered t o th e
diaphragm , th e b ran ch es t i e d and pulm onary and a o r t i o c an n u la s in s e r te d *
C olored w a te r e q u iv a le n t t o one m eter i n h e ig h t was poured th ro u g h th e
a o r t a and a llo w ed t o flo w out o f th e abdom inal a o r ta *
The pulm onary i r r i ­
g a to r was f i l l e d w ith c l e a r w a te r and r a i s e d to v a r io u s l e v e l s t o see
w h eth er th e c o lo re d w a te r would be fo rc e d back from th e a o r ta i n t o th e
pulm onary a r t e r y and a l s o p ass backw ards th ro u g h th e d u o tu s a r t e r i o s u s *
T h is n e v er o c c u rre d when th e cannula in th e pulm onary i r r i g a t o r was a t
a h ig h e r l e v e l th a n th e opening o f th e d u c tu sj when on a lo w er l e v e l ,
th e re v e rs e o c c u rre d , and t h e c o lo re d w a te r flow ed i n t o th e lu n g s th ro u g h
th e d u c tu s a r te r io s u s *
"When th e abdom inal end o f t h e c u t a o r ta was com­
p re s s e d so t h a t th e w a te r flow ed o u t u n d e r p re s s u re and th e pulm onary
-1 6 -
p re s s u re -was "varied, th e c o lo re d w a te r e n te re d t h e pulm onary c an n u la
o n ly when i t s p re s s u re was low er th a n t h a t o f t h e a o r ta *
d ra p e r con­
c lu d e d t h a t no v a lv e a c ti o n was p re s e n t i n th e sen se t h a t S trassm ann
m a in ta in ed *
In a n o th e r experim ent by G raper c l e a r -water was in je o te d i n t o th e
a o r t a a t a p re s s u re o f one m e te r and allo w ed to eso ap e f r e e l y .
C olored
w a te r flow ed o u t o f th e pulmonary a r t e r y and th e n th ro u g h th e a o r t a when
th e pulm onary can n u la was r a is e d above th e a o r t i c opening#
G raper ob­
se rv e d no 4pum p-like a c t i o n r e s u l t i n g from th e r a p i d i t y o f th e o u rr e n t a s
p o s tu la te d by S c h a rfe .
He found t h a t th e flow o o u ld n o t be in c re a s e d by
bending t h e d u c tu s a s was s t a t e d by Linzenm eier#
S im ila r ex p erim en ts on
th e a o r ta w ere c a r r i e d o u t i n w hich th e p re s s u re was v a r ie d by means o f
a cannula up to f iv e m e te rs in le n g th and th e same r e s u l t s a s above w ere
obtain ed *
G raper a l s o perform ed th e fo llo w in g e x p erim en ts i n - s i t u on s t i l l b o m s #
I n je c tio n s w ere made th ro u g h a can n u la p laced i n th e l e f t c a r o t i d a r te r y #
The r i g h t c a r o t i d and b o th ju g u la r v e in s were t i e d a s were a l s o th e v e s s e ls
o f th e e x tr e m itie s #
The u m b ilio a l co rd was c u t c lo s e t o th e u m b ilic u s so
t h a t w a ter c o u ld flow f r e e l y from th e u m b ilio a l a r te r y #
The l e f t p a r t o f
th e th o ra o io w a ll and th e upper lobe o f th e l e f t lu n g were removed i n o rd e r
t h a t th e d u c tu s a r t e r i o s u s oould be observed d u rin g th e i n je c tio n *
Where
n e c e s s a ry p a r t o f th e thymus and same o f th e p e ric a rd iu m was a l s o rem oved.
He found t h a t e v e ry i n j e c t i o n a t p re s s u re s v a ry in g from t h i r t y c e n tim e te rs
t o two m e te rs o f w a te r f i l l e d th e a o r ta and d u ctu s a lm o st im m ed iately and
flow ed o u t o f th e l e f t upper lung#
H is r e s u l t s a r e th e r e f o r e c o n tr a r y t o
th e fin d in g s o f Strassm ann and S c h a rfe in t h a t no v a lv e c o u ld e x i s t a t
th e a o r t i c end o f th e ductus*
-1 7 -
G raper a tte m p te d a f u r th e r t e s t o f th e d is p la c e m e n t and r o t a t i o n
th e o ry by i n f l a t i n g th e lungs and f i l l i n g th e v a s c u la r system w ith warm
p a r a f f in *
On exam in atio n o f th e c a s ts th u s made o f th e d u ctu s a r t e r i o s u s
a f t e r th e p a r a f f i n had o o o le d , o n ly one gave r e s u l t s t h a t m ig h t be
c o n stru e d a s su p p o rtin g th e th e o ry o f d isp la c e m e n t and r o t a t o r y com­
p re s sio n *
G raper s t a t e s t h a t t h i s a p p a re n t r o t a r y com pression m ig h t
a ls o be caused by th e p resen ce of tr a n s v e r s e r id g e s in th e d u c tu s a r ­
te rio s u s •
K ellogg ( ’ 28-29) made s e v e ra l i n j e c t i o n ex p erim en ts on p ig embryos
t o d e te rm in e w h eth er m ixing o f th e two c a v a l stre am s occu rred *
Suspen­
s io n s o f s ta r c h were in je o te d and th e blood su sp e n sio n m ix tu re t e s t e d t o
determ in e th e amount o f m ix in g .
His fin d in g s were in ao co rd w ith th o s e
o f piohlman (*09) in t h a t he a ls o observed m ix in g o f th e two stre am s o f
blood*
H am ilton, Woodbury and Woods ( ’ 36) perform ed e x p erim en ts on newborn
r a b b i t s t o determ ine th e p re s su re r e l a t i o n s h i p s b e fo re and a f t e r b re a th in g *
Hypodermic manometers were in s e r te d in to th e r i g h t and l e f t v e n t r i c l e s
s im u lta n e o u s ly and th e p re s su re d if f e r e n c e s r e s u l t i n g from s e v e r a l m ani­
p u la tiv e s tim u li re c o rd e d .
P e rfu sio n o f th e a o r t a w ith s a li n e s o lu tio n
under p h y s io lo g ic a l p re s su re r e s u lte d i n a d iv id e d stre a m , th e l a r g e r
stream flo w in g from th e a o r ta and th e s m a lle r one back th ro u g h th e d u o tu s,
th u s d e m o n stratin g a re v e rs e flow th ro u g h th e d u ctu s*
S e v e ra l in v e s t ig a to r s made m echanical m odels o f th e f e t a l c i r c u l a t i o n
in w hich th e y a tte m p te d to show by m ech an ical means th e v a rio u s p re s s u re s
in v o lv e d i n changing th e blood flow from th e f e t a l to th e a d u lt ty p e .
Z iegenspeck ( ’02) t r i e d t o j u s t i f y h i s c o n c lu s io n s a s t o th e changes i n
-1 8 -
c i r c u l a t i o n by means o f a diagram and a model*
H is e x p la n a tio n o f i t s
fu n o tio n i s as fo llo w s :
Pig. e.
i
Fig* 5*
Z ieg en sp eck .
I* A lm ost a s much blo o d (L) flow s th ro u g h P&rs oommunicans out o f th e
a rc u s a o r ta e i n t o th e A orta descendens a s flo w s th ro u g h th e lu n g s from
th e tr u n k o f th e pulmonary a r t e r y in to th e l e f t h e a r t*
I I * F u r th e r - a lm o st a s much blo o d flow s th ro u g h th e l e f t opening o f
th e I n f . Vena cava in to th e l e f t h e a r t a s flo w s o u t o f th e u p p er m ain
v e in i n t o th e rig h t*
Summarizing th e flow he s t a t e s t h a t -
B lood volume A -I- Z from r i g h t v e n t r i c l e g iv e s o f f L th ro u g h th e
lu n g s t # th e l e f t h e a r t , so t h a t A 4- Z - L flo w s th ro u g h th e d u o tu s
a r t e r i o s u s in to th e a o r ta descendens*
A +
L from l e f t v e n tr io le goes in t o th e A rcus a o r t a e , A t o u p p e r
body, L o u t th ro u g h th e Arous a o r ta e i n t o th e A o rtae descendens to
t h a t h e re -J- L and - L and A
Z goes i n t o low er body and to th e p la c e n ta .
From t h i s p o in t b o th blood m asses a re r e tu r n e d i n t o th e Vena cava i n ­
f e r i o r , A in to th e l e f t and Z i n t o th e r i g h t h e a r t .
Z ieg e n sp e c k ( ’ 10) c a r r i e s t h i s schema f u r t h e r and co m p iles a n o th e r t h a t
-1 9 -
i s somewhat s im ila r t o t h a t o f Pohlm an.
Z ieg en sp eck assum es t h a t th e
c o n te n t o f each v e n tr ic le i s e q u a l t o 4 and on t h i s b a s is forms th e
fo llo w in g schema o f f o e t a l blood c i r c u l a t i o n .
R.V. s 4 (Lungs
(D uctus
s 2
- 2 A o rta
CavB.
P u l.v e in s - 2 L .V .a 4
a triu m l e f t s 2
= 4
L.V. 5 4 (A o rta
z 2
(Car* & S u b c l. - 2
descendens
in fe rio r
a triu m r i g h t - 2 R.V.
cava s u p e r io r - 2 - 4
The v a rio u s o b je c tio n s to t h i s schema o f blo o d flow a s p u t f o r t h by
Z iegenspeck w i l l be d isc u sse d l a t e r .
S c h a rfe perform ed th e fo llo w in g ex p erim en t w ith th e a p p a ra tu s a rra n g e d
as shown in F ig u re 6 .
Two oamulas - r e p r e s e n tin g th e a o r ta an d th e
pulm onary a r t e r y - hang down from two tu b e s f i l l e d w ith b lu e (A) and re d
(B) c o lo re d w a te r .
A r i g h t a n g le T -tu b e (E ) i s p la ce d in th e pulm onary
a r t e r j and an a cu te a n g u la r one (F ) p la c e d in th e a o r t a .
(D uctus B o t a l l i ) c o n s is ts a g a in of a tu b e (E F ).
The co n n ec tio n
Four clamps ( a , b , c, d)
V
F ig . 1.
F ig . 6 . S c h a rfe
"E-F" D uctus B o t a l l i
above and below th e c o n n ec tio n make p o s s ib le r e g u la tio n o f th e e x p e r i-
—20-
m e n ta l flow and c lo s u r e .
S ch arfe o b ta in e d th e fo llo w in g r e s u l t s w ith
t h i s a p p a r a tu s .
I . I f th e pulmonary (A: b lu e ) i s h ig h e r ( i n t r a u t e r i n e c o n d itio n o f
blood flo w ) th e r e is a flow o u t o f th e pulm onary th ro u g h th e d uctus
and a mixed flow o u t o f th e a o r t a , i . e . , v i o l e t c o lo r e d .
I I . On e q u a l p re s su re in th e a o r ta and pulm onary, i . e . , b o th v e n t r i c u l a r
v e s s e ls e q u a lly h ig h , no flow from one s id e t o th e o th e r o ccu rs and a
flow o f th e b lu e and re d back and f o r t h w ith in th e d u ctu s r e s u l t s .
I I I . I f th e l e f t v e n t r i c l e (re d ) i s h ig h e r th e same r e s u l t i s o b ta in e d
t h a t i s when th e r i g h t v e n t r i c l e i s h ig h e rj v i o l e t f l u i d flow s o u t o f
th e tu b e below because th e s tr o n g e r stream from B ( r e d , a o r t a ) sucks
m%
4
th e b lu e in to th e tu b e w ith i t .
Strassm ann ( ’02) c o n s tru c te d a model o f c i r c u l a t i o n w hich i s b ased
upon t h a t o f S ch arfe (1 9 0 0 ), w hich S trassm ann m a in ta in e d was i n c o r r e c t .
S trassm ann c r i t i c i z e d th e w id th o f th e a o r t i c opening i n S c h a rfe ’ s model w hich
rem ained open a s b e in g in d i r e c t c o n tra stw ith w h a t o ccu rs in l i f e .
Strassm ann a l t e r e d th e system o f S c h a rfe to e lim in a te th e r i g i d i t y
(EF) o f th e tu b e r e p re s e n tin g th e d u c tu s .
T h is was done t o ta k e advantage
o f th e sm all f a l l i n p re s s u re in th e m ain a r t e r i e s .
He made s e v e ra l
diagram s i l l u s t r a t i n g th e v a rio u s a n g le s o f e n tra n c e o f th e d u c tu s in to
th e a o r t a and found t h a t th e s m a lle r th e f a l l in p re s s u re and d e c re a se in
flow th e le s s can th e a c u te a n g u la r e n tra n c e of th e d u ctu s c r e a te a
s u c tio n a s m a in ta in e d by S c h a rfe .
He found t h a t i f a clamp were p la c e d
a t C and D, th e s u c tio n d id n o t c o n tin u e .
In c o n tr a s t to t h i s he found
t h a t i f he in c re a s e d th e p re s s u re i n th e a o r t a ( r e d ) a o r t i c blo o d flow s
th ro u g h th e a c u te a n g u la r e n tra n c e to w ard th e pulm onary a r t e r y .
He found
-2 1 -
th e r e f o r e t h a t S c h a rfe 1s work c o u ld n o t be c o r r e c t s in c e th e a n g le o f
e n tra n c e o f th e d u ctu s i n t o a o r ta mu3t be more th a n 40° t o w ork and
a ls o t h a t a much h ig h e r p re s s u re i s n ecessary *
S tie n o n (*12) o b ta in e d re p ro d u c tio n s o r c a s t s o f th e lumen o f th e
d u ctu s and i t s a d ja c e n t v e s s e ls by i n j e c t i n g a m ass o f p l a s t e r in to
th e descending a o r ta from below u n d e r s l i g h t p r e s s u r e .
These c a s ts
o f newborns were s tr ip p e d o f t h e i r v a s c u la r c o v e rin g s t o d is c lo s e th e
c h a r a c t e r i s t i c s o f th e a r t e r i a l c a n a l and of th e a o r t i c is th m u s .
S tien o n
a ls o c a r r ie d o u t ex p erim en ts s im ila r to th o se o f Strassm ann b u t a r r iv e d
a t e n t i r e l y d i f f e r e n t c o n c lu s io n s .
He found t h a t he co u ld e a s i l y i n j e c t
th e ductus th ro u g h th e descending a o r t a , b u t t h a t i t was n o t p o s s ib le to
F ig . 7 . S tie n o n
See Fig* 1 and 4*
-2 2 -
do so i f one fo rc e d th e i n je c te d mass u n d e r a slow and m oderate
p re s s u re th ro u g h a v e s s e l o f th e n e c k .
His e x p la n a tio n o f t h i s r e s u l t
d i f f e r s from t h a t o f Strassm ann in t h a t i n i n j e c t i n g th e m s s from be­
low upwards in to th e descending aorta, th e mass e n te r s th e d uctus and
th e isthm us o f th e aorta, s im u lta n e o u s ly .
In i n j e c t i n g from above down­
w ard i t " d is te n d s th e isth m u s, com presses and d e p re ss e s th e c a n a l o f
B o ta l w hich c e a s e s t o be p e rm e ab le ."
L inzenm eier ( ’14) fo llo w e d a p ro c e d u re s im i la r to t h a t o f S tien o n
in making c a s t s o f th e i n t e r i o r o f th e duotus i n a newborn t h a t had n o t
b re a th e d , on f iv e f e t u s e s , th r e e p rem atu res and two newborns (See F ig .
4 , page 1 4 ).
Rehman and Noback (*37) c a r r ie d o u t a stu d y o f th e topography and
r e l a t i o n s h i p s o f th e th o r a c ic v is c e r a by moans o f o rth o s c o p ic draw ings,
photographs and c a s t s .
The c a s t s , which were made o f each su c c e ss iv e
s ta g e o f d i s s e c tio n , i l l u s t r a t e d th e to p o g rap h y a c c u r a te ly .
Measurements
and o th e r o b s e rv a tio n s were a ls o made and re c o rd e d .
EMBRYOLOGICAL STUDIES
Many in v e s t i g a t o r s have s tu d ie d th e d u c tu s from an a n a to m ic a l o r
p h y s io lo g ic a l p o in t o f view b u t few have been concerned w ith i t s embry­
o lo g y .
K iw isoh (1851) d e sc rib e d th e o r i g i n o f th e d u ctu s in th e embryo
a s a r i s i n g from a change o f th e a rc h e d v e s s e ls o f th e b r a n c h ia l a p p a r a tu s .
The lo w est a rc h on th e r i g h t d is a p p e a rs up t o th e o r ig i n o f th e pulm onary
a rte ry .
I t rem ains open on th e l e f t and forms t h e ductus a r t e r i o s u s w hich
u n it« r w ith th e f o u r th a r c h w hich form s th e a o r t i c a rc h and i s u n ite d t o
th e descending p a r t .
In th e f o e tu s th e d u ctu s i s a c o n tin u a tio n o f th e
pulmonary a r t e r y and b e g in s above th e o r ig i n o f b o th pulmonary a r t e r y
b ra n c h es and c o n tin u e s from t h i s p o in t b en d in g s l i g h t l y upwards and
-2 3 -
p o s t e r i o r l y in to th e descen d in g p a r t o f th e a o r t i c a r c h "below th e l e f t
s u b c la v ia n a r t e r y .
R oeder ( '0 2 ) was a l s o i n t e r e s t e d i n th e developm ent
o f th e d u ctu s b u t fro n th e s ta n d p o in t o f h is to lo g y .
He found t h a t th e
a n t e r i o r w a ll o f th e d uctus d e v e lo p n e n ta lly forms a comraon s t r u c t u r e w ith
th e a o r t i c w a l l .
He named t h i s th e u n i t i n g p o r tio n (v e rb in d u n g s k e il) and
d e s c rib e s i t a s f u n c tio n a lly a c ti n g a s a v a lv e - lik e c o v erin g over th e
a o r t i c opening a t th e p la c e o f t r a n s i t i o n o f th e a ro h o f th e a o r ta in to
th e descending a o r t a .
He i s i n ag reem en t w ith S trassm ann re g a rd in g th e
presenoe o f a v a lv e - lik e s t r u c t u r e a t t h i s p o in t.
H o c h s te tte r (*06) a g re e s w ith K iw isch (1851) and o th e rs a s t o th e
o r ig i n o f th e d u ctu s b u t s t a t e s t h a t i t undergoes a seco n d ary le n g th e n in g .
Sclavounos ( ’ 11) tr a c e d th e developm ent o f th e d u c tu s to d eterm in e th e
o r ig i n o f a pulm onary r i d g e .
He found t h a t each p a r t o f th e m ain tru n k
o f th e pulm onary tru n k in th e embryo i s developed a s c o l l a t e r a l b ran ch es
o f th e r i g h t and l e f t pulm onary a r t e r i e s , w hich d iv id e t h i s tr u n k in to
two p o r tio n s , one s u p e rio r o r c e p h a lic , and one i n f e r i o r o r c a u d a l, and
t h a t th e s u p e r io r p o rtio n becomes th e d u c tu s .
The lum ina o f th e s e
l a t e r a l branohes e n la rg e a t b i r t h , w ith r e s p i r a t i o n , a t th e expense of
th e p o s te r io r w a ll of th e tr u n k and th u s form th e pulm onary r i d g e .
Ivlelka ( ’ 26) s tu d ie d th e d u ctu s in embryos ra n g in g i n le n g th from
5 .5 c e n tim e te rs up to 25 c e n tim e te r s .
He d e s c rib e d th e h i s t o l o g i c a l
s t r u c t u r e o f th e d uctus i n t h e embryo i n o rd e r t o w ork o u t th e c o u rse
o f developm ent o f th e d u c tu s and i t s c l o s u r e .
COMPARATIVE ANATOMY
The com parative anatomy o f t h e d u c tu s has n o t b een e x te n s iv e ly s tu d ie d
a lth o u g h m ention o f i t s e x is te n c e i n v a rio u s low er v e r te b r a te form s has bsai made in
-2 4 -
s e v e r a l w o rk s.
Ilo c h s te tte r ( '0 6 ) s tu d ie d th e embryology- and com parative
anatomy o f th e d u ctu s in th e U ro d eles and found t h a t th e s i x t h a o r t i c
a ro h w idens o n ly t o th e p la c e o f o r i g i n o f th e pulm onary a r t e r y whose
d o rs a l s e c tio n i s known a s th e d u c tu s B o t a l l i .
b u t v e ry weak.
T h is rem ain s p a te n t
He found in th e Anuran t l i a t th e rem ainin'g'“a o r t i c a rc h e s
a t th e b e g in n in g o f m etam orphosis when th e g i l l a rc h e s a tro p h y develop
from, th e e f f e r e n t a r t e r y and th e b e g in n in g s e c tio n o f th e a f f e r e n t a r t e r y .
As in th e U ro d e le s, th e f i f t h a o r t i c a rc h d is a p p e a rs on b o th s id e s and
a ls o th e o b l i t e r a t i o n of the m ost d o rs a l p ie c e o f th e s i x t h a o r t i c a rc h
(d u c tu s B o t a l l i ) betw een th e b e g in n in g o f th e a r t e r i a cu tan e a magnn and
d o rs a l a o r t i c r o o t tslces p la c e .
lie found t h a t th e b i r d shows s im ila r de­
velopm ent t o th e r e p t i l e .
H am ilton, Y/oodbury and Y.'oods (*37) i n t h e i r s tu d y o f th e d uctus in
dog and r a b b i t f e tu s e s , found t h a t i t d if f e r e d somewhat from t h a t o f th e
human.
They d e sc rib e a v a lv e in th e d u ctu s of th e dog t h a t i s s im ila r to
t h a t d e sc rib e d by Strassm ann f o r th e human.
AHAT0I.1ICAL COIJSIJBKATIOHS
The f i r s t known m en tio n of th e term "d u ctu s a r t e r i o s u s " o ccurs in
th e works o f G u ilio C esare A ra n zi who liv e d from 1530 to 1589.
He does
n o t however g e n e r a lly re c e iv e c r e d i t f o r d is c o v e rin g i t because i t a p ­
p e a rs in h is "Die humo fo e tu l i b e r " p u b lis h e d i n 1595, w hich d id n o t
a p p ea r u n t i l a f t e r h is d e a th .
The d u o tu s a r t e r i o s u s was named a f t e r a
contem porary o f h i s , Leonardus B o ta llu s , who d is c u s s e d th e f e t a l c i r c u l a ­
t i o n and whose main i n t e r e s t was in th e foram en o v a le , b u b w h o d id in cid en tally
m ention th e d u ctu s a r t e r i o s u s .
In re g a rd to t h i s q u e s tio n , i t i s i n ­
t e r e s t i n g t o n o te th e fo llo w in g q u o ta tio n from Harvey (1 6 2 8 ), "And t h i s
-2 5 -
oircum stanoe i t w as, p e rh a p s, t h a t imposed upon B o ta llu s , who th o u g h t he
had d isc o v e re d a new p assag e f o r th e blood from th e vena cava in to th e
l e f t v e n t r i c l e o f th e h e a r t ."
H arvey had e v id e n t ly s tu d ie d th e duotus
f o r he d e s c rib e s i t a s "a k in d o f a r t e r i a l c a n a l, c a r r i e d o b liq u e ly from
th e vena a r t e r i o s a , o r pulm onary a r t e r y , to p e r f o r a t e and te rm in a te in
th e a r t e r i a magna o r a o r t a . "
"The c a n a lis a r t e r i o s u s c o n ta in s no membrane
o r valve t o d i r e c t o r impede th e flo w o f th e b lo o d i n t h i s or in t h a t
d ir e c tio n , f o r a t th e r o o t o f th e vena a r t e r i o s a , o r pulmonary a r t e r y , o f
which th e c a n a lis a r t e r i o s u s i s th e c o n tin u a tio n i n th e f e t u s , th e re a re
th re e sigm oid o r sem ilu n ar v a lv e s . . . . when th e h e a r t c o n tr a c ts , th e blood
i s r e g u la r ly p ro p e lle d by th e c a n a l o r p assag e in d ic a te d from th e r i g h t
v e n t r i c l e in to th e a o r t a ."
Harvey d id n o t go i n t o any f u r t h e r d e t a i l a s
to th e anatomy o f th e d u ctu s o r th e su rro u n d in g s t r u c t u r e s .
H is i n t e r e s t s
were c e n te re d p rim a rily upon th e th e o r y o f c i r c u l a t i o n .
K ilia n (1826) s tu d ie d th e c i r c u l a t o r y system i n th e s t i l l b o r n new­
born c h ild and concluded t h a t th e pulmonary a r t e r y and duotus a r t e r i o s u s
a re th e same ty p e o f v e s s e l a s th e a o r t a .
K ilia n o b serv ed t h a t in th e
fo u r t o s i x week embryo th e a o r t a and pulm onary a r t e r y a re o f th e same
c o n s tr u c tio n b u t s e p a ra te d from e ac h o th e r f o r a sm all d is ta n c e o n ly .
The a d ja c e n t sid e w a lls o f b o th v e s s e ls w hich grow from below upward
form a common p r o je c tin g w a ll a t th e u n io n o f th e d u ctu s and a o r t a .
Strassm ann (1894) a ls o r e f e r r e d t o a •v a lv e -lik e s t r u c tu r e a t t h i s p o in t
and e v id e n tly had based h i s f in d in g s p a r t l y upon th o s e o f K ilia n .
Above
th e ju n c tio n o f th e ductus and a o r ta K ilia n found t h a t th e lumina o f b o th
v e s s e ls wore s i m i l a r .
On exam ining "em bryos" (new borns) of a few days
he found t h a t th e pulmonary a r t e r y to be o f th e same s iz e as th e duotus
-2 6 -
and c a rry in g a l l th e blo o d from th e r i g h t v e n t r i c l e o f th e h e a r t to th e
a o rta .
On removing th e p e rio a rd iu m th e v e s s e l was found to le av e th e
r i g h t h e a r t and ru n a s a n i s o l a t e d v e s s e l f o r a s h o r t d is ta n c e and th e n
e n te r in to union w ith th e d escen d in g a o r t a .
F ig . 8 .
K ilia n
(See F ig s . 8 and 9 ) .
F ig . 9 .
K ilia n
K ilia n s e c tio n e d th e d u c tu s lo n g i tu d in a lly and found i t to be an
" u n in te rru p te d c a n a l" c o n ta in in g "no v a lv e s o r in te r r u p t io n s " and o f
uniform th ic k n e s s s im ila r t o th e s t r u c t u r e found in a r t e r i a l w a l l s .
The w a ll
(" s h e a th " ) o f th e " s o - c a ll e d pulmonary a r t e r y " (d u c tu s a r ­
t e r i o s u s ) was a deeper re d th ro u g h o u t th a n th e w a ll o f th e a o r t a .
lie
e x p la in s th e d iff e r e n c e in c o lo r a s b e in g due to d a rk e r blood c i r c u l a t i n g
in th e pulmonary a r t e r y th a n in th e a o r t a .
The d u o tu s in i t s co u rse to
th e a o r ta slo p ed o b liq u e ly upwards from r i g h t to l e f t and was s l i g h t l y
-2 7 -
b e n t from b e fo re backw ard.
The a n g le o f e n tra n c e o f th e duotus in to th e
a o r ta was v e ry a c u te , w ith th e d u ctu s ly in g a lo n g s id e th e a o r t a f o r a
s h o r t d is ta n c e and u n ite d to i t by c e l l u l a r m a t e r i a l .
The le n g th o f th e
d uctus was n o t g iv e n , b u t th e d is ta n c e from th e h e a r t to th e a o r ta was
s t a t e d t o be one in c h .
The diam eter o f th e lumen was found t o be t h a t o f
a q u i l l and s u b je c t t o a g r e a t d e a l o f v a r i a t i o n .
He found t h a t th e
lumen of th e d uctus d e crea se d in d ia m e te r as th e d u ctu s n e ared th e a o r ta
and th e p la c e o f e n tra n c e o ccu rred where th e r e c u r r e n t la ry n g e a l nerve
cu rv es around th e a o r t a .
The su b c la v ia n a r t e r y a r i s e s th r e e to fo u r
"L in ien " ( l i n e s l / l 2 in c h ) to th e r i g h t of t h i s .
He found th e r e f o r e t h a t
th e a o r ta ( to th e l e f t o f th e o r ig in o f th e s u b c la v ia n a r t e r y ) does nob
form th e a o r t i c a rc h b u t a c t u a l l y form s th e d u c tu s a r t e r i o s u s .
A narrow ­
in g o f th e lumen o f th e a o r ta o ccu rs d i s t a l to th e o r ig in o f th e sub­
c la v ia n a r t e r y and a f t e r re c e iv in g th e duotus th e lumen o f th e a o r ta
w idens a g a in .
month on,
T h is d if f e r e n c e oan be re c o g n iz e d from th e f o u r th f e t a l
Iiany subsequent w orkers b ased t h e i r th e o r ie s o f c lo s u re upon
th e a n a to m ic a l fin d in g s o f K ilia n w hich a re n o t e n t i r e l y a c c u r a te .
**
King (1840) d e sc rib e d th e d u ctu s a s a r i s i n g from th e b if u r c a t i o n o f
th e pulmonary a r t e r y and c o n tin u in g a s a tem porary tu b e to end in th e
a o r ta n e a r th e "summit o f th e descen d in g p o r ti o n ."
The d iv is io n o f th e
tra c h e a o c cu rred c lo se behind th e m iddle o f th e a rc h o f th e a o r ta and th e
l e f t bronchus curved downward to th e l e f t i n t o th e lung c ro s s in g a n t e r i o r
o r in f r o n t o f th e descending a o r t a .
The l e f t bronchus th e r e f o r e p a sse s
b e n e a th th e d u ctu s a r t e r i o s u s and b eh in d th e l e f t pulm onary a r t e r y .
He
found th e topography o f th e th o r a c ic v is c e r a was such t h a t th e r e was
" c lo s e packing in th e unborn c h ild even more rem arkable th a n l a t e r . "
In
-2 8 -
l a t e r l i f e th e c h e s t c o n tin u e d o f a lim it e d c a p a c ity , th e diaphragm
h ig h and th e lu n g s co n fin ed a b o u t th e h e a r t*
He fo rm u la te d a th e o ry
o f c lo s u r e b ased upon an e rro n e o u s i n t e r p r e t a t i o n o f th e anatom y found
in th e newborn t h a t had b re a th ed *
R okitanslcy (1844) m erely d e s c rib e s
th e d u ctu s a s th e c o n tin u a tio n o f th e pulm onary a r t e r y w hich "bends round
tow ards th e descending a o r ta in th e form of th e f u tu r e d u ctu s a r te r io s u s * "
H is work w hich i s fr e q u e n tly q u o te d , c o n ta in s no f u r t h e r r e fe re n c e to th e
c o u rse o f th e ductus*
Langer (1857) made an e x te n s iv e s tu d y o f th e anatom y o f th e f e t a l
c i r c u l a t i o n and c o rre c te d some o f th e e r r o r s made by p re v io u s in v e s t ig a ­
to rs ,
He found t h a t a g r e a t d if f e r e n c e e x is t e d betw een th e s t r u c tu r e o f
th e pulmonary a r t e r y , a o r ta and ductus i n th e f iv e and seven month old
fe tu s ,
lie a ls o observed no n o tic e a b le d if f e r e n c e in th e th ic k n e s s o f
d i f f e r e n t p a r ts o f i t s w a ll and he m a in ta in e d t h a t th e in n e r s u rfa c e was
smooth*
The f u l l - t e r m s t i l l b o r n d if f e r e d however in t h a t th e ira lls of th e
d u c tu s '."-ore s tr o n g e r than th e pulmonary a r t e r y and a o r ta and t h i c k e r on
one s l u e .
The in n e r s u rfa c e had l o s t i t s sm oothness and c o n ta in e d lo n g i­
t u d i n a l rid g e s t h a t resem bled broken down f i b e r s ( f ib r o u s t i s s u e ) .
F ig . 10,
Langer
He a ls o found t h a t , sin c e th e co u rse o f th e ductus was o b liq u e , th e m argin
o f b o th c o n ic a l lu n im i l i e ag o i:\n t th o a o r ta a n t e r i o r l y and on th e r i g h t
pulm onary b ra n o h .
Wrany (1871) d e sc rib e d th e d u ctu s a r t e r i o s u s a s a c o n ic a l, red u ced
c o n tin u a tio n o f th e pulmonary a r t e r y .
I t s c o u rs e slo p ed somewhat up­
w ard, l a t e r a l l y and p o s t e r i o r l y so t h a t i t e n te r e d th e low er w a ll o f th e
a o r ta a t a more o r l e s s a c u te angle*
I t s p la c e o f e n tra n c e was lo c a te d
a b o u t th r e e t o fo u r m illim e te rs from th e o r ig i n o f th e s u b c la v ia n a r t e r y .
The d uctus passed f o r some m illim e te r s o f i t s c o u rse over th e su rro u n d in g
f o ld o f p e ric a rd iu m i n th e p o s t e r io r m ediastinum and la y imbedded in a
v e ry lo o se c o n n ec tiv e tis s u e *
Schanz (1889) in h is stu d y o f th e m e ch a n ic al c lo s u r e o f th e d u ctu s
examined th e anatomy o f th e th o r a c ic v is c e r a in in f a n ts t h a t had b re a th e d
a s w e ll a s in in f a n ts t h a t had n o t b r e a th e d .
!Iis d e s c r ip t i o n
o f th e
anatomy in v o lv e d , a lth o u g h r a th e r e x te n s iv e , i s n o t e n t i r e l y a c c u ra te *
he found t h a t th e th o ra x was s m a lle r in a l l i t s m easurem ents in a c h ild
t l i a t had n o t b re a th e d , th e diaphragm was h ig h , th e h e a r t r a t h e r h o r i ­
z o n ta l and re a c h in g p o s t e r i o r l y t o th e v e r t e b r a l column upon b o th s id e s
o f w hich th e a t e l e c t a t i c lungs r e s t e d .
He found, in a c h ild t h a t had b re a th e d , t h a t th e th o ra x was expanded
th e r i b s and sternum r a is e d and th e diaphragm lo w ered .
The h e a r t had
s h i f t e d i t s p o s itio n away from th e v e r t e b r a l column andtils i n t u r n had
caused th e more p o s te r io r p a r t o f th e diaphragm t o s i n k .
The lu n g s had
in c re a s e d in volume and c o n se q u e n tly th e pulm onary h i lu s w hich had p r e ­
v io u s ly r e s te d a g a in s t th e v e r t e b r a l column was now moved to th e m iddle
o f th e th o r a c ic c a v i t y .
The e n tra n c e o f th e d u c tu s i n t o th e a o r ta had
however undergone v e ry l i t t i e change in p o s i t i o n .
I t s e n tra n c e i n t o th e
a o r ta o c cu rred a t th e p la c e where th e a o r t a was fa s te n e d to th e v e r t e b r a l
column by c o n n e c tiv e t i s s u e m asses and by th e bran o h es o f th e a o r t a .
As
-3 0 -
a r e s u l t th e a o r t i c end o f th e d uctus was fix e d in p la c e .
The o th e r
end a r i s i n g a t th e pulmonary b if u r c a tio n was e n clo se d in p e ric a rd iu m
and n o t fix e d in p la c e .
T his end,
i f p u lle d upon th e r e f o r e , would be
s h i f t e d somewhat in p o s itio n .
Dwight 6; n o tc h (1691) d id n o t m ention th e d u ctu s in t h e i r work on
th e " th o ra x in in fa n c y " ,
however,
th e y d e sc rib e d th e p o s itio n
thymus b u t f a i l e d to n o te i t s r e l a tio n s h i p to th e d u c tu s .
o f th e
They s t a t e d
t h a t th e thymus extended a " fin g e rb re a d th " above th e sternum and i n f e r i o r l y a s two long lo b es on th e p eric ard iu m i n th e a n t e r i o r m ed iastin u m .
These lo b es l i e t o e i t h e r sid e o f th e m id lin e and a re a s y m e tr ic a l, th e
th ic k e r p o rtio n ly in g b ehind th e f i r s t p ie ce o f v a n u b riu n s t e r n i and
r e s t i n g on th e h e a r t and g r e a t v e s s e l s .
I t th u s o v erlap p ed th e innom i­
n a te v e in , th e s u p e rio r vena cava and th e a rc h o f th e a o r ta and ex ten d ed
p o s te r io r ly a s f a r a s th e tr a c h e a .
I t extended more i n f e r i o r l y i n t o th e
a n g le betw een th e p e ric ard iu m and th e p le u r a .
The a re a occupied by th e
thymus was found to alm ost e q u al t h a t o f th e l e f t lu n g .
P o s te r io r l y
th e thymus ex tended behind th e o n tc r io r m argin o f th e v e r t e b r a l column
and a ls o betw een th e s u p e r io r vena cava and th e tr a c h e a .
The g r e a t e r
p a r t o f th e thymus was found to l i e t o th e l e f t o f th e m id lin e #
I t may be o f i n t e r e s t to m ention a t t h i s p o in t t h a t Symington
(1687) in h is c la s s ic a l work f a i l e d t o m ention th e d u c tu s .
Dwight
(1 8 8 1 ), iJ itte n h e im e r (1894-) p rep ared c ro s s s e c tio n s o f newborns and an
i n f a n t b u t d id n o t in c lu d e th e ductus e i t h e r in t h e i r p la te s or d e s ­
c r i p t i v e m a tte r .
LJBttenheimer (1894) c a r r ie d o u t a work s im ila r t o Dwight and Rotchf/*'}/^
b u t h is o b s e rv a tio n s d i f f e r from th o se o f th e p re v io u s in v e s tig a to r s #
-3 1 -
He found th e thymus t o c o n s is t o f two u n e q u a lly developed lo b e s w hich
a t f i r s t a re c lu b -sh a p e d from above downward; th e g r e a t e r p a r t ly in g
more m ed ial and
th e l e s s e r p o rtio n more l a t e r a l *
Hed iv id e d th e thymus
in to a c e r v ic a l
and a th o r a c ic p o rtio n ; th e th o r a c ic p o r tio n b ein g
g r e a t e r and ly in g u n d e r th e manubrium and body of th e sternum from th e
ju g u la r n o tc h t o th e t h i r d i n t e r c o s t a l sp a c e .
fu rth e r in te r io r ly ,
th y r o id g la n d .
The thymus may e x ten d
even to th e diaphragm and ex ten d s u p e r io r ly to th e
The p o s te r io r su rfa c e r e s t s on th e p e ric a rd iu m and c o v ers
th e la rg e v e s s e ls a t t h e i r o rig in *
I t may o c c a s io n a lly re a c h
p o s te rio rly
t o th e tr a c h e a and i t s l a t e r a l e x te n s io n s re a c h to th e b i f u r c a ti o n o f th e
tr a c h e a .
I t th e r e f o r e occupied much o f th e u p p er and a n t e r i o r p a r t o f
th e m ediastinum and when g r e a tly developed may to a g r e a t e x te n t p r o je o t
p o s te rio rly ,
be a ls o m issed th e in tim a te r e l a t i o n s h i p betw een th e thymus
and th e ductus*
The work o f Strassm ann (1694-1002) w i l l bo d is c u s s e d more f u l l y th a n
t h a t o f p re v io u s i n v e s t i g a t o r s .
His fin d in g s a re im p o rta n t because th e y
have formed th e b a s is o f th e th e o r ie s of s e v e ra l su b seq u en t in v e s tig a to r s *
S trassm ann d id n o t ag ree w ith p re v io u s w orkers in t h e i r o b s e rv a tio n s r e ­
g a rd in g th e change in p o s itio n or bending o f th e d u ctu s t h a t o c cu rred
when i t was assumed to be empty o r p a r t i a l l y so and r e s p i r a t i o n liad s e t
in .
flo w .
He p o s tu la te d t h a t th e changes in th e h e a r t were due t o changes in
The p e ric a rd iu m was d e sc rib e d as b ein g s a c - lik e and n o t s u f ­
f i c i e n t l y s tro n g onoiw.k to p u ll on th e ductus and cause k in k in g *
He
m a in ta in e d t h a t th e d e sc e n t o f th e diaphragm, c o u ld n o t cause th e
c lo s u re o f th e ductus sin c e th e p e ric a rd iu m moved w ith th e change in
p o s itio n o f th e lu n g s .
These c o n c lu sio n s were drawn from h is o b s e rv a tio n s
-3 2 -
on th e th o r a c ic c o n te n ts o f th e newborn human t h a t had n o t b r e a th e d .
He s t a t e d t h a t th e th o ra x was expanded by th e r a i s i n g o f th e sternum
and r i b s an d th e d e p re s s io n o f th e diaphragm .
The thymus was found to l i e
on th e h e a r t , and th e innom inate v e in p a r tly covered th e a o r t i c a r c h .
On
removing th o r a c ic organs th e l a s t p a r t only o f th e ductus ( a t th e a o r t i c
e n tra n c e ) c o u ld be s e e n .
The a n t e r i o r p a r t of th e p e ric a rd iu m was opened
t o expose th e r o o ts o f th e la r g e v e s s e l s .
These proceeded a n t e r i o r l y b e ­
tw een th e two a u r i c l e s , w hich were s e p a ra te d by a d is ta n c e ra n g in g from
s e v e r a l m illim e te r s to a b o u t th r e e - q u a r te r s o f a c e n tim e te r .
th e pulm onary a r t e r y was lo c a te d a t t h i s p o in t.
The bulb o f
The d u ctu s a ro s e from
th e pulm onary a r t e r y and c o n tin u e d s u p e r io r ly , l a t e r a l l y , and p o s t e r i o r l y
to e n te r th e concave u n d e rsid e o f th e a o r t a .
The d ia m e ter o f th e duotus
was alm o st e q u al t o t h a t o f th e a o r ta and i n t h e i r course th e two v e s s e ls
a lm o st p a r a l l e l e d each o t h e r .
The e n tra n c e o f th e d u c tu s i n t o th e a o r t a
t h e r e f o r e formed a v e ry a cu te a n g le ; th e e n tra n c e o c c u rrin g a l i t t l e below
th e o r i g i n o f th e l e f t su b c la v ia n a r t e r y where th e a r c h o f th e a o r t a con­
tin u e d a s th e d escending a o r t a .
h i s d iag ram .
(T his d e s c r ip tio n d i f f e r s m arkedly from
See F ig . 12, p g . 3 5 ) .
T his p o r tio n o f th e a o r t a l i e s t o
th e l e f t of th e t h i r d th o r a c ic v e rte b ra or s l i g h t l y s u p e r io r and in
l i n e w ith th e sy n ch o n d ro sis o f th e second and t h i r d v e r t e b r a .
The
l e f t bronohus ra n under th e a o r t i o a rc h and duotus a r t e r i o s u s t o th e
l e f t lu n g , th e l e f t branoh of th e pulmonary a r t e r y ly in g a n t e r i o r l y
to th e b ro n c h u s.
The l e f t vagus nerve c ro s se d th e l e f t s u b c la v ia n
a r t e r y and wound round th e duotus and a rc h o f th e a o r t a .
The l e f t
r e c u r r e n t la r y n g e a l n erve a ls o curved around th e s e s t r u c t u r e s and
c o n tin u e d upward t o th e h e a d .
The d uctus a r t e r i o s u s , a c o n tin u a tio n
-3 3 -
o f th e pulm onary a r t e r y , vms n o t dem arcated from th e pulmonary a r t e r y
by any f o l d s .
The two pulm onary a r t e r i e s th e r e f o r e appeared t o be
s id e b ra n c h es of th e m ain tru n k (pulm onary tru n k anu i t s c o n tin u a tio n ,
th e d u ctu s a r t e r i o s u s ) .
His c l e a r d e s c r ip ti o n o f th e v a rio u s p o r t io n s of th e ■orbr. lo c a te
a c c u r a te ly f o r us th e p o in t o f on France of th e u u ctu s in to th e a o r t a .
The a rc h of th e a o r ta b e g in s a t th e o r ig i n o f th e innom inate a r t e r y
and e x ten d s to th e l o f t su b c la v ia n a r t e r y as a c y l i n d r i c a l tu b e .
The
th re e main v e s s e ls a r i s e frcsr:: th e a rc h o f th e a o r ta by means o f round
o p en in g s; t h a t of th e innom inate a r t e r y i s la r g e r tlian th e o th e r tw o.
Strassm ann found th e d is ta n c e betw een th e innom inate a r t e r y and
th e l e f t common c a r o tid a r t e r y , a t t h e i r o r ig i n , to be sm a lle r th a n t h a t
betw een th e l e f t common c a r o tid a r t e r y and th e l e f t s u b c la v ia n a r t e r y .
(T h is does n o t ag ree w ith th e m easurem ents and fin d in g s o f t h i s s tu d y ) .
The l e f t bronchus ( i n a hardened specim en) on i t s way to th e l e f t lung
l i e s behind th e concave s u rfa c e o f th e a rc h o f th e a o r t a .
T h is r e s u l t s
in an im p ressio n on th e e x t e r i o r and a shallow rid g e on th e in n e r s u r­
fa c e o f th e b ro n c h u s.
A f te r g i v i n g o f f th e th r e e main b ran ch es th e a o r t i c a rc h narrow s
to form th e "isthm us o f th e a o r t a " .
The few m illim e te rs o f th e a o r ta
s e p a ra tin g th e b eg in n in g o f th e l e f t su b c la v ia n a r te r y and e n tra n c e
o f th e d uctus in to th e a o r ta has been c a lle d th e "p ara communicans"
(Z ieg en sp eck ) o f th e f o e t a l a o r t a .
Strassm ann m a in ta in e d t h a t th e above d e s c r ip tio n s a ls o a p p lie d to
dog and c a t f e tu s e s upon w hich he had perform ed v a rio u s i n j e c t i o n
e x p e rim e n ts.
The l i n i n g o f th e d u ctu s r e s s c a rre d and o f brow nish
-3 4 -
c o lo r .
The c o v erin g o v e r th e v a lv e - li k e s tr u c t u r e whore th e duotus
e n te r s th e a o r ta was found to be somewhat sm oother and l i g h t e r in c o lo r
th a n th e rem ainder o f th e in tim a o f th e d u c tu s .
S tu d ie s were a ls o
c a r r ie d o u t on newborn and s t i l l b o r n k i t t e n s o b ta in e d by means o f
c a e s a r ia n s e c tio n .
He d e sc rib e d a d e f in it e f o ld t h a t o v erlap p ed th e
e n tra n c e o f th e d u c tu s .
v e ry wide and g a p in g .
In th e f iv e month f e tu s t h i s e n tra n c e was
T his was somewhat m o d ified by th e s ix th month
to c o n ta in a r a t h e r d e f i n i t e r i d g e - li k e fo rm a tio n .
D uring th e se v e n th
month th e w a ll moved f u r t h e r over th e a o r t i c e n tra n c e so t h a t i t a p ­
peared narrow er and s lit- f o r m e d .
The o o u rse o f th e d u ctu s changed to
become more curved and ru n downward.
(See F ig . 3, p g . 1 1 .)
Strassm ann d e sc rib e d tixe changes in man a s o c c u rrin g tow ard th e
end o f th e eighth, month as p re p a ra tio n s f o r th e m ech an ical c lo s u r e o f
H il H uud uutl K iU e »uiiprli>K<n iiu r 2 ir o n * G i I I i h «u* dim AartasbM W Am Mrt*. Aw
T tu o id i • o m j'in u i, » en d tt d l . b ild e n I'.nM ldui aui a id bU d li l u i d ll l*AhM A lt H W W k
Daa l o r l i . f it ill* link* Art. tubetoti*.
7>ur I llu s tra tio n dien c F ig. 4 . In otwft d o p p e lte r V ergriM *r u n g g io h t sie dio V crh iiltn isso w ieder, w ie aie boi eiuem eb e n fille
10 T ag e a lie n w oiblichen H un d eh en d esselben W urfes, t o o dec
d a s zu v o r e rw a h n te T liior sta m tn te , gefan d en w ard en (S ection II.,
24 . Mai 1 8 9 2 ). Dio S ch leffch a u t des D uotus, d e r n io h ts e n th ie lt,
F ig . 1 1, Nos. 3 & 4 , Strassmann.
-3 5 -
th e d u c tu s .
The d uctus c o u rse s in an "unopened a rc h -sh a p e d c u rv a tu re t o
i t s o b liq u e e n tra n c e in to th e a o r ta whose w a ll co v ers o v er th e e l l i p t i c a l
s l i t - l i l c e opening in a v a lv e - lik e m anner.
The e n tra n c e however i s o fte n
v e ry wide and th e v a lv e - lik e f o ld v e ry l i t t l e d e v elo p e d ."
The change in
p o s itio n o f th e diictus and th e a o r ta was found to be only r e l a t i v e in th e
n in th and t e n t h f e t a l months u n t i l b i r t h .
An in c re a s e in c a l i b e r d id
o ccu r; th e grow th of th e d uctus b ein g as ra p id a s th e pulm onary a r t e r i e s .
The d u ctu s reach ed i t s maximum s iz e a t b i r t h ; b u t th e p r o je c tio n o f th e
ductus in to th e a o r t i c m i l co u ld o n ly be n o tic e d in th e empty c o n d itio n .
The d u ctu s now opened in to th e i n f e r i o r and l a t e r a l w a ll o f th e a o r ta
where i t becomes th e d escending p o r tio n .
The co v erin g o f th e e n tra n c e
by th e p r o je c tio n o f th e a n t e r i o r w a ll was e a s i l y seen by S trassm an n .
The opening o f th e ductus a r t e r i o s u s i n to th e a o r ta p r o g r e s s iv e ly changed
from th e f i f t h month to b i r t h , becoming more s l i t - l i l c e over whioh cpenipgtharede­
velo p ed a r i d g e - l i k e o r " v a lv e - lik e " p r o je c tio n o f th e proxim al h a l f o f
■vrrwy.
■i‘ h ' t
Sami topo**
la tk a a * aorta*.
. .•.
O a tla n lo r ilc u n n l r u l l f a r a i
* r t* r le * L
A a tti d w N o d u f .
F ig .
1 2 , S tr a ssm a n n .
■
' yy'
-3 6 -
th e a rc h i n th e new born.
T his m s formed by means o f a d u p lic a tu r e o f
th e a n t e r i o r m i l of th e d u ctu s w ith th e a o r t i c w a l l .
He found th e
same c o n d itio n t o e x i s t a l s o i n sh eep , c a t and dog f e t u s e s .
Strassm ann*s
o b s e rv a tio n s have been q u e stio n e d by s e v e ra l i n v e s t i g a t o r s .
His f i n d -
in g s seem t o have been based p r im a r ily upon sheep and dog f e tu s e s r a t h e r
th a n upon human m a t e r i a l ,
H un tin g to n (18D7) s tu d ie d th e th o ra x in f iv e f e tu s e s a t te rm , fo u r
newborns and two f e tu s e s o f 25 and 31 w eeks,
lie does n o t r e f e r to th e
ductus a lth o u g h h is work i s concerned c h ie f ly w ith th e s t r u c t u r e s in th e
immediate v i c i n i t y of th e d u c tu s .
He observed th e im p ressio n s made by
th e thymus on th e m ed ial su rfa c e o f th e lungs b u t he did n o t, however,
e x ten d th e a re a s f a r enough p o s t e r i o r l y a c c o rd in g t o Nobaok.
C u i U i K itiv ij
Knee
F ig .
1 3 . H u n tin g to n
F ig . 1 4 . H untington
The
-3 7 -
p o in te d shape o f th e a p io a l p o r tio n o f th e lung o f th e e a r l i e r s ta g e s i s
changed t o th e more q u a d ra n g u la r form o f th e o ld e r lung by th e e x p an sio n
o f th e u p p er lo b e i n a s a g i t t a l d ir e c tio n *
In th e o ld e r lu n g th e p o s t e r i o r
m argin i s d i r e c t l y a lm o st h o r i z o n t a l l y th u s b rin g in g th e apex i n t o d i r e c t
c o n tin u a tio n w ith th e a n t e r i o r m a rg in .
L a te r, a t te rm , th e ex p an sio n o f
th e u p p er and a n t e r i o r segm ent o f t h e s u p e rio r lo b e r e s t o r e s th e apex t o
i t s p o s itio n a s th e u p p e r rounded te r m in a tio n o f th e p o s te r i o r m a rg in .
T h is o b s e r v a tio n o f H u n tin g to n 's f i t s in v e ry w e ll w ith th e d a ta o f t h i s
stu d y and i s an a d d itio n a l f a c t o r in th e e x p la n a tio n o f th e c lo s u r e o f
th e ductus*
The a re a c o v ered by th e thymus a c c o rd in g to H u n tin g to n was found t o
be q u ite e x te n s iv e .
The r i g h t in n o m in ate v e in and s u p e r io r vena cava
l i e b eh in d th e thym ic a r e a ; th e r i g h t p h re n io n erv e d escen d in g betw een
th e s u p e r io r vena cava
The r i g h t l a t e r a l w a ll o f th e
k h ». x x v i l
F ig . 15*
H u n tin g to n .
F ig . 1 6 .
H u n tin g to n
tra o h e a was s e p a ra te d from th e la r g e venous tru n k s i n f r o n t b y a
q u a n tity o f f a t t y c o n n e c tiv e t i s s u e and sm all ly m p h atic g la n d s .
The
-3 7 -
p o in te d shape o f th e a p io a l p o r tio n o f th e lung o f th e e a r l i e r s ta g e s i s
changed t o th e more q u a d ra n g u la r form o f th e o ld e r lung by th e e x p an sio n
of th e u p p er lo b e i n a s a g i t t a l d i r e c t i o n .
In th e o ld e r lung th e p o s t e r i o r
m argin i s d i r e c t l y a lm o st h o r i z o n t a l l y th u s b rin g in g th e apex in to d i r e c t
c o n tin u a tio n w itfi th e a n t e r i o r m a rg in .
L a te r , a t te rm , th e expansion o f
th e u p p er and a n t e r i o r segm ent o f t h e s u p e rio r lo b e r e s t o r e s th e apex t o
i t s p o s itio n a s th e u p p er rounded te r m in a tio n o f th e p o s te r io r m arg in .
T h is o b s e r v a tio n o f H u n tin g to n 's f i t s in v e ry w e ll w ith th e d a ta o f t h i s
stu d y and i s a n a d d itio n a l f a c t o r in th e e x p la n a tio n o f th e c lo s u re o f
th e d u c tu s .
The a re a c o v ered by th e thymus a c c o rd in g to H u n tin g to n was found to
be q u ite e x te n s iv e .
The r i g h t innom inate v e in and s u p e rio r vena cava
l i e b e h in d th e thym ic a r e a ; th e r i g h t p h re n ic n erv e d escen d in g betw een
th e s u p e r io r vena cava and th e thym us.
The r i g h t l a t e r a l w a ll o f th e
*
ft*
F i g . 1 5.
H u n tin g to n .
F ig . 1 6 .
H untington
tra o h e a was s e p a ra te d from th e la rg e venous tru n k s in f r o n t by a
q u a n tity o f f a t t y c o n n e c tiv e t i s s u e and sm all lym phatic g la n d s .
The
-3 6 upper t h i r d o f th e m e d ia s tin a l a r e a o f th e r i g h t lung c o n ta in e d th e
thym ic im pression*
The upper p a r t o f t h e m ediastinum c o n ta in s th e thymus w h ile th e
low er ( p o s te r io r ) p a r t i s oooupied by th e p e ric a rd iu m w hich i s c ro s se d
o b liq u e ly by th e l e f t p h re n ic n e rv e .
At th e u p p er and p o s t e r io r m argin
o f th e l e f t pulm onary r o o t , th e a ro h o f th e a o r ta produoes a marked
e le v a tio n o f th e m e d ia s tin a l p le u r a , w hich i s c o n tin u e d alo n g th e e n ­
t i r e p o s te r io r b o rd e r o f th e m ediastinum by th e d escen d in g th o ra o ic
a o r t a , th e e le v a tio n becoming l e s s m arked a s th e a o r ta approaches th e
diaphragm*
Above th e l e v e l o f th e upper h i l u s m a rg in , between th e
v e r te b r a l column p o s t e r i o r l y and th e thymus g la n d a n t e r i o r l y th e
m e d ia s tin a l p le u ra c o v e rs th e l e f t m argin o f th e esophagus, th e i n t r a th o r a c ic p o rtio n o f th e l e f t s u b c la v ia n a r t e r y which form s a prom inent
rounded rid g e on th e m e d ia s tin a l w a ll and th e l e f t oommon c a r o tid a r t e r y
and vagus n e rv e .
Below th e h i l u s o f th e l e f t lung th e p e ric a rd iu m p ro ­
j e c t s in to th e l e f t p l e u r a l c a v it y alo n g th e p o s te r io r i n f e r i o r p a r t
o f th e m e d ia s tin a l s u rfa o e o f th e l e f t lu n g .
Above th e p e r i c a r d i a l a re a
th e m ed ial su rfa c e o f th e l e f t lu n g r e s t s on th e m e d ia s tin a l p le u ra
o o v e rin g th e l a t e r a l s u r f a c e o f th e thymus g la n d .
T h is thymus s u rfa c e
i s p lan e o r s l i g h t l y oonvex and s e p a ra te d from th e p e r io a r d i a l de­
p re s s io n by a r a i s e d c u rv ed m a rg in , w ith th e c o n c a v ity fa c in g i n f e r i o r l y and p o s t e r i o r l y and c o rre sp o n d s to a cu rv ed groove s e p a ra tin g th e
thymus i n - s i t u from th e p e ric a rd iu m .
The m ed ial su rfa o e o f th e l e f t lung i s grooved by th e a rc h o f th e
a o r ta above th e h i l u s .
T h is groove b e g in s a s a f a i n t d e p re ss io n on
w hich r a p id ly deepens t o i t s g r e a t e s t d e p th j u s t above and b eh in d th e
s u p e r io r p o s t e r i o r a n g le o f th e h i l u s .
(The fin d in g s o f th e p re s e n t stu d y
-3 9 -
show t h a t th e d e e p e s t g ro o v in g i s oaused by th e d u c tu s a r t e r i o s u s b e­
coming p a r t i a l l y imbedded i n th e lu n g ) .
A t t h i s p o in t a n a rro w e r, deep ,
n e a r ly v e r t i c a l groove p a ss e s s u p e r io r ly t o th e u p p er m argin o f th e
lu n g .
The i n tr a th o r a o ic p o r tio n o f th e l e f t s u b c la v ia n a r t e r y p ro ­
duces t h i s g ro o v e •
Between th e su b c la v ia n groove p o s t e r i o r l y , th e u p p er b o rd e r of
th e a o r t i c groove below , th e up p er lu n g m arg in ab o v e, and th e thym io
s u rfa o e in f r o n t , th e m e d ial s u rfa o e o f th e l e f t lu n g p re s e n ts a smooth,
n e a r ly plane f i e l d which r e s t s on th e m e d ia s tin a l p le u r a c o v e rin g th e
proxim al p a r t o f th e l e f t common c a r o t i d a r t e r y and th e l e f t vagus n erv e
imbedded i n a q u a n tity o f f a t t y and g ra n u la r c o n n e c tiv e t i s s u e .
Behind th e h i l u s th e a o r t i c groove o o n tin u e s t o be m arked, d e s ­
cending n e a r ly v e r t i c a l l y , and c an be fo llo w e d t o th e lo w er b o rd e r o f
th e lu n g , grow ing g ra d u a lly s h a llo w e r.
Below th e h i l u s , and i n f r o n t o f th e low er p o r tio n o f th e a o r t i c
g ro o v e , th e m e d ia l lung s u rfa o e p r e s e n ts a w e ll m arked t r i a n g u l a r p ro c e ss
w hich can be c a l l e d , w ith re g a rd t o i t s r e l a t i o n s , th e p e r ic a r d io - e o s o p h ag eal tu b e r o s ity (H u n tin g to n ).
I t oooupies th e t r i a n g u l a r re o e e s be­
tw een th e a o r ta b ehind and th e p e ric a rd iu m i n f r o n t and c o n ta in s a t th e
bottom th e l e f t w a ll o f th e oeso p h ag u s.
The m arked grooving o f th e
m ed ial s u rfa c e o f th e u p p er lo b e o f th e l e f t lung by th e d u o tu s , d e s­
c rib e d by Uobaok ( '3 5 , '3 7 ) was a p p a r e n tly n o t o b serv ed by H u n tin g to n
f o r nowhere does he m ention t h i s obvious a n a to m ic a l e n t i t y .
C h ie v itz (1889) r e p o r te d on th e s tu d y o f th e to p o g ra p h ic anatom y
o f b u t one f u l l - t e r m f e t u s .
The diaphragm was found t o be l e s s s tr o n g ly
a rc h e d in th e f e t u s th a n i n th e a d u l t .
The apex o f th e h e a r t was tu rn e d
§
-4 0 -
a lm o s t d i r e o t l y fo rw a rd .
The upper end was c lo s e t o th e sternum and
e x ten d e d backward a lm o st h o r iz o n ta ll y , b e in g co v ered by th e thym us.
From th e p o s t e r i o r end o f t h i s s u rfa c e t h e pulm onary a r t e r y p a ss e s
backw ards in a h o r iz o n ta l and n e a r ly s a g i t t a l d ir e o ti o n and h av in g
g iv e n o f f th e r i g h t and l e f t pulm onary a r t e r i e s from i t s u n d er a s p e o t,
i t i s c o n tin u e d a s th e duotus a r t e r i o s u s , w hich a f t e r a s h o r t o o u rse
jo i n s th e a o r t a , b e in g c ro s s e d by th e vagus nerve a t th e p o in t o f
ju n c tio n .
The a o r ta comes in o o n ta c t w ith th e f o u r th th o r a c ic v e r te b r a
and i s jo in e d a t t h i s p o in t by th e d u o tu s .
he a l s o f a i l e d to o b serv e
th e r e l a t i o n s betw een th e d u o tu s , th e lung an d th e thym us.
Kusohew (*01) s tu d ie d a n e x te n s iv e s e r i e s o f 205 cad av ers ra n g in g
in age from f e tu s e s o f 25, 27, 37, 45 and 50 c e n tim e te rs th ro u g h th e
new born, i n f a n t , o h ild , and a d u lt s ta g e s .
H is s tu d y was p r im a r ily con­
c e rn e d w ith th e m aorosoopio s tr u c tu r e o f th e d u o tu s a f t e r b i r t h .
how ever, s e c tio n e d and s ta in e d tw e n ty -e ig h t duotw.
He,
The d u ctu s was found
t o a r i s e from th e b if u r c a tio n o f th e pulm onary a r t e r y i n 9 2.6$ o f th e
o a se s s tu d ie d .
No m ention however i s made a s t o th e o r i g i n o f th e r e ­
m ain in g 7 .4 $ .
The duotus te rm in a te d on th e i n f e r i o r w a ll o f th e a o r t i o
a ro h where i t became th e d escend in g a o r t a .
T h is p o in t he lo c a te d a t
a b o u t 2-3 mm. b e lo w .th e o r ig i n o f th e l e f t s u b c la v ia n a r t e r y .
The a o r tio
end o f th e d u ctu s was fu n n e l-sh a p e d and th e r e f o r e l a s t t o c l o s e , le a v in g
an im p ressio n on th e a o r tio s u r f a c e .
Roeder (*02) was th e f i r s t in v e s t i g a t o r to m easure th e a n g le formed
by th e e n tra n c e o f th e duotus i n t o th e a o r t a .
T h is a n g le w hich was found
t o be 33° forms th e b a s is o f h is e x p la n a tio n o f th e f e t a l ty p e o f c i r ­
c u la tio n .
He m a in ta in e d t h a t i f t h i s a n g le w ere g r e a te r and th u s
-4 1 approached a r i g h t a n g le , a s e p a r a tio n o f th e stre a m s o f flo w form ing
th e la rg e and sm all o i r c u l a t i o n w ould be im p o ssib le*
Jaokson (*09) made re c o n s tr u c tio n s o f s e v e r a l young embryos and
i n h is a n a to m ic a l d e s c r ip tio n e rro n e o u s ly s t a t e d t h a t th e d u o tu s g iv e s
r i s e t o th e pulmonary a r t e r i e s *
Solavounos ( '1 1 ) exam ined th e pulmonary a r t e r y and found a rid g e
betw een th e two lum ina o f th e pulm onary b ra n c h es and t h i s rid g e e n oroaohed on th e p o s te r io r w a ll o f th e pulmonary a r te r y *
The two p u l­
monary branohes approach each o th e r and th e p o s t e r i o r edge o f th e two
lum ina m eet and u n ite th u s form ing a p a r t i t i o n w hich form s th e body o f
th e pulm onary rid g e *
The s u p e r io r p a r t o f t h i s pulmonary rid g e fu s e s
a t r i g h t a n g le s w ith th e rid g e o f th e d u o tu s .
T h is rid g e in th e duotus
a c o o rd in g t o Solavounos th e r e f o r e l i e s a t th e b e g in n in g o f th e d u o tu s,
betw een th e pulm onary tru n k and th e duotus*
F ig u re 17 shows th e a n a ­
to m ic a l r e l a t i o n s o f th e pulmonary tr u n k , duotus a r t e r i o s u s and a o r ta
q u ite a o c u r a te ly , b u t Solavounos f a i l e d to d e s o rib e th e to p o g ra p h ic
anatom y o f th e reg io n *
•v:
w f 1’
Fig* 17*
Solavounos.
-4 2 -
S tie n o n ( '1 2 ) s tu d ie d th e oan&l o f B o ta l (d u o tu s a r t e r i o s u s ) in
a la r g e number o f newborn i n f a n t s , some o f w hich were s t i l l b o r n (th e
e x a c t number i s n o t g iv e n )*
The p u rp o se o f h is s tu d y o f th e duotus
was t o examine th e o h a r a o t e r i s t i o s o f i t s a o r t i o and pulm onary con­
n e c tio n s in a n e f f o r t t o determ ine th e cause o f i t s o b l i t e r a t i o n *
Re­
p ro d u c tio n s o f th e lum ina o f th e d u ctu s and a d ja c e n t v e s s e ls w ere made
by means o f p l a s t e r in je c tio n s *
In th e s t i l l b o r n th e d u ctu s a r i s e s a s
th e d ir e o t c o n tin u a tio n o f th e pulm onary a r t e r y and c o n tin u e s i t s c u r­
v a tu r e , a sc e n d in g t o tho l e f t where i t l i e s u n d er th e r o o t o f th e
is th m u s •
I t c ro s s e s th e l e f t pulmonary a r t e r y , w hich S tie n o n f in d s
t o be 6 t i l l ru d im e n ta ry , and fo llo w s th e isth m u s to te rm in a te i n th e
a n t e r o - i n t e r n a l p a r t o f th e descen d in g a o r ta b e n e a th i t s p o in t o f u n io n
w ith th e isthm us*
The e n tra n c e in to th e a o r ta form s a v e ry a o u te a n g le
whose " s in e i s d ir e c te d fo rw a rd s, upw ards, and t o th e r i g h t . "
7 , page 21)*
(F ig u re
I t s e n tra n o e ta k e s up a b o u t o n e - th ir d o f th e d ia m e te r o f
th e a o r t a .
S tie n o n m a in ta in s t h a t a c o n s id e ra b le amount o f m o d if ic a tio n ooours
a f t e r re s p ir a tio n has s e t i n .
The d u o tu s i s no lo n g e r th e d i r e o t con­
t i n u a t i o n o f th e pulm onary a r t e r y , b u t a r i s e s a t a r i g h t a n g le from i t *
The l e f t pulm onary a r t e r y expands and c r o s s e s th e d u o tu s a t a b o u t th e
m id d le o f i t s l e n g th .
th e p re s e n t s tu d y .
T his r e l a t i o n s h i p has n o t onoe been o b serv ed in
The isthm us o f th e a o r t a i s g r e a t l y e n la rg e d and
le n g th e n e d and th e r e f o r e com presses and re d u c es th e a o r t i c mouth*
(R e fe r to F ig . 7 , No* 1 , page 21)*
A ccording t o F aber (* 1 2 ), th e d uotus b e fo re b i r t h i s a t h i c k tu b e
t h a t i s s t r a i g h t and. c o n tin u o u s w ith th e pulm onary a r t e r y ru n n in g
-4 3 -
g ra d u a lly o b liq u e ly from above t o i t s opening in to th e a o r t a .
A f te r
b i r t h i t becomes t h i n n e r and a d e f i n i t e zone d e lim its i t from th e p u l­
monary a r t e r y .
I t now ru n s in an a rc h over th e l e f t pulmonary a r t e r y
and l e f t b ro n c h u s.
Faber a t t r i b u t e s th e change w hich o ccu rs betw een
th e pulm onary a r t e r y an d th e d u c tu s a f t e r b i r t h a s due t o th e f i l l i n g
o f th e l e f t pulmonary a r t e r y and a s a r e s u l t o f t h i s th e l e f t pulm onary
a r t e r y p r e s s e s a g a in s t th e main p a r t o f th e pulm onary t r u n k .
The d u c tu s
th e r e f o r e i s changed from a f r e e l y p a te n t v e s s e l t h a t opens f r e e l y i n t o
th e a o r ta b e fo re b i r t h t o a t h i n , o b liq u e ly -d ra w n c a n a l, w ith i t s lum en
reduced i n c a l i b r e .
The p o r tio n o f th e d u ctu s opening in to th e a o r ta
makes a 90° a n g le ( a t v a ria n c e w ith th e fin d in g s o f o th e r i n v e s t i g a t o r s )
b e fo re b i r t h and t h i s a n g le becomes more a c u te w ith age so t h a t th e open­
in g i n t o th e a o r ta becomes n a rro w e r and l a t e r form s a tr a n s v e r s e c l e f t .
A s h i f t i n g i n th e to p o g ra p h y o f t h e th o ra c io s t r u c t u r e s i s th e r e f o r e a s ­
sumed t o o ccu r a f t e r b i r t h .
Gundobin ( ’ 12) a l s o r e p o r te d t h a t th e d uotus a r i s e s from th e p o in t
o f b i f u r c a t i o n o f th e pulm onary a r t e r y and in some c a se s from th e l e f t
pulm onary a r t e r y .
However, he was u n a b le t o f in d any case i n w hich th e
ductus a r o s e from th e l e f t pulm onary a r t e r y and th e r e f o r e one i s le d t o
i n f e r from t h i s s ta te m e n t t h a t he i s q u o tin g th e work o f some o th e r i n ­
v e s t i g a t o r (p ro b a b ly Kuschew).
The e n tra n c e o f th e d u o tu s i n t o th e
a o r ta was found t o l i e i n th e low er w a ll (" u n te re wand” ) o f th e d es­
cending p a r t o f th e a o r t a .
The le n g th and th ic k n e s s d e c re a se some
days a f t e r b i r t h .
F e t t e r o l f and G ittin g s ( ’ 11) and G itt in g s , F e t t e r o l f and M itc h e ll
( ’ 16) d e s c rib e d th e to p o g rap h y o f th e th o r a c ic v is c e r a i n i n f a n t s b u t
-4 4 -
f a i l e d t o d e s c rib e o r m e n tio n th e d u o tu s o r ligam entum a r t e r i o s u a .
The pulm onary a r t e r y i n th e i n f a n t l i e s t o th e l e f t and s l i g h t l y a n t e r i o r
t o th e a o r t a and d iv id e s in to a lo n g r i g h t b ran o h and a s h o r t l e f t
b ra n c h .
The thymus w hich s e p a r a te s t h e pulmonary a r t e r y from th e a n ­
t e r i o r o h e s t w a ll, i s baoked on th e l e f t by a mass o f s o l i d t i s s u e w hich
l i e s betw een th e u p p er lobe o f th e thymus a n t e r i o r l y and th e tra c h e a
p o s te rio rly .
The thymus i s r e l a t i v e l y la rg e and ex ten d s beyond th e
b o rd e rs o f th e stern u m , w id e ly s e p a r a tin g th e u p p er lo b e s o f th e two
lu n g s .
The upper m edian p o r tio n o f th e thymus o o n ta in s a deep in d e n ta ­
t i o n p o s t e r i o r l y form ed by th e l e f t i n n o m i n a t e v e in .
The p o s te r io r and
l a t e r a l e x te n t o f t h e thymus i s n o t d e s c rib e d a t any g r e a t e r d e ta il*
A more d e t a i l e d and th o ro u g h s tu d y o f th e thymus and i t s to p o g ra p h ic
r e l a t i o n s was c a r r ie d o u t by Noback (* 2 1 ) .
A s e r i e s c o n s is tin g o f s i x t y -
f iv e f e tu s e s and f u l l - t e r m in f a n ts ra n g in g from 10 to 55 c e n tim e te r was
examined w ith r e fe re n c e to th e changes o o c u rrin g a t b i r t h and i n th e
p e rio d o f th e new born.
Mobaok found t h a t th e morphology o f th e thymus
was determ ined i n e a r l y f e t a l l i f e ; th e o n s e t o f r e s p i r a t i o n had no e f ­
f e c t in changing i t s l o b a tio n .
The thymus i n th e l a t e f e tu s was found
to be p re d o m in a n tly o f a c e r v io o -th o ra o io ty p e .
The p o s it io n was i n t e r ­
m ediate betw een t h a t o f th e c e r v i c a l lo c a t io n in th e embryo and th e
th o ra c io p o s i t i o n i n l a t e r l i f e .
The form and r e l a t i o n s w ere found t o
be ty p i c a l and c o n s ta n t i n th e l a t e f e t u s and s t i l l b o r n .
The l a t e r a l
s u rfa c e s o f th e thymus i n th e s t i l l b o r n a r e convex and i n c o n ta c t w ith
th e m ed ial s u rfa c e o f th e lungs b u t th e lu n gs do n o t o f te n ex ten d on to
th e a n t e r i o r s u r f a c e .
The thymus r a r e l y ex ten d ed on to th e a n t e r i o r s u r ­
fa c e o f th e r i g h t v e n t r i c l e o f th e h e a r t .
-
45 -
The m orphology and to p o g ra p h ic r e l a t i o n s o f th e thymus in th e l i v e b o rn traze found t o d i f f e r from t h r o o f th e l a t e f e t u s .
The thymus b e ­
came e lo n g a te d and moulded a s a " r e s u l t o f com pression" by th e n e ig h ­
b o rin g s t r u c t u r e s ; th e lu n g s now e x te n d in g o v er th e l a t e r a l p a r t o f th e
a n te rio r su rfa c e .
T his ohange i n form from th e b ro ad o r f e t a l ty p e t o
th e e lo n g a te d , moulded ty p e o f th e liv e b o r n i n f a n t i s d i r e o t l y dependent
upon th e e s ta b lis h m e n t o f r e s p i r a t i o n and th e d eg ree o f ex p an sio n o f th e
lu n g s .
As a r e s u l t o f t h i s e x p an sio n o f th e lu n g s "th e thymus i s cam-
p re s s e d on b o th s id e s by th e m e d ia l s u rfa c e s o f th e expanding lungs and
a ls o a n te r o - p o s te r io r ly by th e a n t e r i o r b o rd e rs o f th e lu n g s w hich e a r l y
become much th ic k e n e d in th e e s ta b lis h m e n t o f r e s p i r a t i o n and g ra d u a lly
o v e rla p th e thym us."
(N obaok).
Noback ( ’21) a ls o found t h a t in "some c a s e s th e thymus may e x ten d
p o s t e r i o r l y to such an e x te n t t h a t s t r u c t u r e s th e r e a re com pressed by i t .
T his may be due e i t h e r t o a n u n u s u a lly la r g e thymus c r to a v e ry n arro w ,
s u p e rio r th o r a c ic a p e r tu r e w hich w i l l n o t a llo w th e thymus t o p ro tru d e
in to th e c e r v ic a l re g io n as i t i s com pressed by th e expanding lu n g e ."
T h is o b s e rv a tio n i s a v e ry im p o rta n t f a c t o r to be c o n sid e re d i n any ex­
p la n a tio n o f th e c lo s u re o f th e d u ctu s and i s one o f th e v i t a l f a c to r s
o f th e th e o ry p u t f o r t h in th e p re s e n t s tu d y .
Soammon ( '2 3 ) d e s o rib e s th e d u o tu s a r t e r i o s u s a s a " s h o r t tru n k
co n n ectin g th e pulm onary a r t e r y w ith th e u p p er p a r t o f th e descending
a o r t a ."
I t " jo in s th e a o r t a a t i t s m e d ia l b o rd e r j u s t below th e p o in t
o f o r ig in o f th e l e f t s u b c la v ia n a r t e r y . "
The e lo n g a te d a o r t i c o r i f i o e
o f th e duotus c o n ta in s a f l a p w hich Soammon b e lie v e s to be S tra ssm a n n 's
-
46 -
v a lv e o f th e duotus a r t e r i o s u s and w hich i s a c t u a l l y a f o l d betw een th e
d u o tu s and th e a o r t a .
The d u o tu s i s e x t r a p e r i c a r d i a l and i n c o n ta c t w ith
th e l e f t bronohus belcrw and th e thymus g la n d co v ers i t a n te r io r l y *
d ra p e r ( ’ 21) s tu d ie d tw en ty d u o tu s and found them t o be c o n tin u a tio n s
o f th e pulmonary a r t e r y ; bendin g g r a d u a lly i n t h e i r c o u rs e so t h a t no com­
p r e s s io n (JKnickung11) r e s u l t e d .
The d ia m e te rs o f th e lum ina o f b o th p u l­
monary a r t e r i e s were s m a ll, th e l e f t showing a deep rid g e t h a t had been
pushed in from behind so t h a t th e lumen d id n o t a p p e a r c i r c u l a r in c r o s s s e c tio n .
The c o u rse o f th e duotus was concave below and underw ent th e
g r e a t e s t bending in th e m id d le , b ein g b e n t tow ard th e l e f t and ly in g c lo se
to th e a o r t i c a r c h .
The opening in to th e d escen d in g a o r ta a t an a n g le o f
30-33° (R oeder) was such t h a t th e d u o tu s and a o r ta w ere fu se d a t th e en ­
tr a n c e o f th e duotus and th e r e f o r e resem bled a v a lv e (S trassm an n ) when
c u t i n lo n g itu d in a l s e c tio n *
G raper ( ’26) s tu d ie d th e f e t a l th o ra x and th e changes o c c u rrin g
a fte r b irth .
The a n t e r i o r p l e u r a l f o ld s form ed two p e rp e n d ic u la r alm o st
p a r a l l e l r id g e s in th e m id -re g io n o f th e wide f e t a l th o r a x .
The thymus
e x ten d s on b o th s id e s i n t o th e p l e u r a l c a v ity so t h a t th e p le u r a l fo ld s
oover th e p e rio a rd iu m .
The f l a t c h e s t of th e f e t u s w ith th e r i b s ru n n in g
o b liq u e ly changes a t th e f i r s t i n s p i r a t i o n so t h a t th e r i b s a re r a i s e d .
The r ib s s in k a g a in a t e x p ir a ti o n b u t n o t t o th e p re v io u s le v e l*
W ith
su c c e ss iv e b re a th s th e r i b s r i s e h ig h e r so t h a t th e th o r a c cage becomes
h ig h ly a rc h e d and th e a n t e r i o r c h e s t w a ll i s r a i s e d a n t e r i o r l y and
c ra n ia lly .
is a lte re d .
The thymus undergoes a d e c re a se i n i t s m id d le and i t s shape
The shape o f th e h e a r t i s fix e d and i t t h e r e f o r e r o t a t e s
so t h a t th e apex moves more a n t e r i o r l y and th e sternum o ra n ia lw a rd s
in c r e a s in g th e space betw een th e a n t e r i o r c h e s t w a ll and t h e g r e a t
-
v e s s e ls .
47 -
The thymus i s fo r c e d in to t h i s spaoo m aking use o f t h i s com­
p le m e n tary sp a c e .
As th e p le u ra moves fo rw ard a n o th e r "com pl4mentary
space" i s form ed.
D ragendorf (*29) found t h a t th e a o r t i c a rc h i n th e newborn i s
f l a t t e r th a n in l a t e r l i f e and th e d u o tu s i s p la c e d d i r e o t l y a g a in s t
th e a o r t i c a rc h in th e new born.
A f te r b i r t h th e r o o ts o f th e a r t e r i e s
a re r a i s e d , th e a o r t i c a ro h becomes h ig h e r and a g r e a t e r space i s
formed betw een th e a o r tio a ro h and d u c tu s a r t e r i o s u s .
At i t s be­
g in n in g th e duotus forms a c o n tin u a tio n o f th e pulm onary a r t e r y and
th e n c o n tin u e s a s a f l a t , upward ben d in g a ro h w hich e n te r s th e d e s ­
cen d in g a o r ta below th e isthm us a t an a n g le o f 33° (R o e d e r).
The a o r t i c
e n tra n c e i s o b liq u e and th e r e f o r e o v a l.
Rehman ( '3 7 ) d e so rib e d th e c o u rse o f th e d uotus as p a s s i n g o b liq u e ­
ly to th e l e f t and p o s t e r i o r l y to e n te r i n t o th e a n t e r o - l a t e r a l su rfa o e
o f th e descending a o r ta a b o u t one c e n tim e te r d i s t a l t o th e o r ig i n o f th e
l e f t su b c la v ia n a r t e r y .
The a n g le form ed by i t s e n tra n c e i n t o th e a o r ta
i s more a c u te th a n t h a t s t a t e d by R oeder and by G ra p er.
The form o f th e
duotus v a r i e s , a lth o u g h s e v e ra l c l a s s i f i c a t i o n s may be made.
The to p o ­
g ra p h ic r e la tio n s h ip s o f th e d u ctu s t o n e ig h b o rin g s tr u c t u r e s a re giv en
in d e ta il.
The thymus was found to l i e in c o n ta o t w ith th e a n t e r i o r
l a t e r a l and s u p e r io r s u rfa c e s o f th e d u c tu s and th u s a c t a s an a n t e r i o r
l a t e r a l com pressing fo ro e upon th e d u o tu s .
The f l a t t e n e d a o r t i o a ro h
was s e p a ra te d from th e d uotus by a sm a ll c re s c e n t-s h a p e d s p a c e .
The
d uotus r e s t e d upon th e l e f t bronchus m e d ia lly and i n f e r i o r l y and grooved
th e m e d ia l s u rfa c e o f th e l e f t lung l a t e r a l l y .
T his d e s c r ip tio n o f th e
oourse and to p o g ra p h io r e l a t i o n s h i p s d i f f e r s somewhat from t h a t o f o th e r
in v e s t i g a t o r s , i n t h a t th e oourse was fo u n d t o be more d i r e o t l y a n te r o -
-4 8 -
p o s t e r i o r and i t s e n tra n c e i n t o th e a o r ta same d is ta n c e d i s t a l t o th e
s u b c la v ia n a r t e r y .
COURSE OF THE DUCTUS ARTERIOSUS
K ilia n (1826) d e s c rib e d th e c o u rse o f th e duotus a s " o b liq u e ly
s lo p in g upwards from r i g h t t o l e f t and s l i g h t l y b e n t from b e fo re b ack ­
w a rd ."
Langer (1857) m e re ly d e s c rib e d th e c o u rs e o f th e d uotus a s b e in g
o b liq u e , h av in g an a rc h -sh a p e d c o u rse r e s u l t i n g in a s h o r t e r p o s t e r io r
w a ll.
W alkoff (1868) found th e d u ctu s t o be th e c o n tin u a tio n o f th e
pulm onary a r t e r y c o u rs in g o b liq u e ly upward, l a t e r a l l y and p o s t e r i o r l y t o
te rm in a te a t an a n g le i n th e m e d ia l p a r t o f th e a o r ta a b o u t th r e e to
fo u r m illim e te r s from th e o r ig in o f th e l e f t su b c la v ia n a r t e r y .
T h is
e n tra n o e th e r e f o r e o c cu rs s e v e r a l m illim e t e r s from th e e n c lo s u re o f th e
p e ric a rd iu m and w ith in th e p o s te r io r m ediastinum in a space embedded in
c o n n e c tiv e t i s s u e t h a t i s poor i n f a t .
C h ie v itz (1899) d e sc rib e d th e c o u rse o f th e d u ctu s i n more d e t a i l .
He found t h a t th e pulm onary a r t e r y a r i s e s from th e h e a r t and p a sse s b ack ­
w ard in a h o r iz o n ta l and n e a r ly s a g i t t a l d i r e o tio n and a f t e r g iv in g o f f
th e r i g h t and l e f t pulmonary a r t e r i e s from i t s "under" a s p e c t , i s con­
tin u e d a s th e duotus a r t e r i o s u s , w hich a f t e r a s h o r t c o u rse jo in s th e
a o r ta and i s c ro s se d by th e vagus n erv e a t th e p o in t o f ju n c tio n .
The
d u ctu s j o i n s th e a o r t a a t th e le v e l o f th e f o u r t h d o r s a l v e r t e b r a .
Roeder (*02) m easured th e a n g le formed by th e u n io n o f th e duotus
and a o r ta and found i t t o be 3 3 °.
His th e o ry o f flow o f th e sy stem ic and
pulmonary c i r c u l a t i o n s i s based upon t h i s m easurem ent.
I f th e a n g le be­
comes g r e a t e r , a p p ro ach in g a r i g h t a n g le , th e s e p a r a tio n o f b o th stream s would
be q u ite im p o s s ib le .
He p o s tu la te d on t h i s b a s i s th e v iew t h a t th e a n g u la r
-4 9 -
and a rc h e d form o f arrangem ent o f th e duotus an d a r c h o f th e a o r ta was
th e o n ly form a b le to 'w ith stan d th e hemodynamic f o r c e s r e s u l t i n g i n th e
v e s s e ls t h a t d o s e to th e h e a r t .
T h is maimer o f e n tra n o e made p o s s ib le
th e a b i l i t y to w ith s ta n d th e p re s s u re r a i s e d by th e a c u te a n g u la r n arro w ­
in g .
As a r e s u l t o f t h i s th e a b i l i t y to c lo s e m s in v e r s e ly p r o p o r tio n a l
t o th e s iz e o f th e a n g le .
A rgaud (*05) b a sin g h is fin d in g s upon th e stu d y o f b u t one f iv e m onth
o ld f e tu s d id n o t a g re e w ith form er i n v e s t ig a to r s re g a rd in g th e c o u rse o f
th e d u c tu s .
The pulm onary tr u n k , a f t e r h av in g g iv en o f f two b ra n c h e s ,
sw e lls o u t in to a o o n ic a l o u l- d e - s a c , from th e apex o f w hich th e a r t e r i a l
canal a r i s e s .
The duotus th e n c o n tin u e s upward and e n te r s th e o o n o a v ity
o f th e a o r t i c a ro h .
K ir s te in ( ’ 10) found th e d uotus i n c lo s e o o n ta c t w ith
th e a o r t a , s e p a ra te d from i t o n ly by t h i n c o n n e c tiv e t i s s u e and smooth
m u sc le .
F aber ( '1 2 ) d if f e r e d w ith th e se i n v e s t i g a to r s a s to th e c o u rse
and a n g le o f e n tra n o e o f th e duotus in to th e a o r t a .
He d e s c rib e d th e
duotus a s a th ic k tu b e co n tin u o u s d i r e c t l y w ith th e pulm onary a r t e r y and
c o n tin u in g g ra d u a lly o b liq u e ly from above to th e a o r ta b e fo re b i r t h .
A f te r
b i r t h i t becomes th in n e r and ru n s in an a rc h o v er th e l e f t pulm onary
a r t e r y and l e f t b ro n o h u s.
The a n g le formed by i t s e n tra n o e i n t o th e
a o r ta i s 90° a t b i r t h and becomes more a c u te w ith a g e .
i s c o n tr a r y t o th e fin d in g s o f o th e r i n v e s t i g a t o r s .
T h is o b s e r v a tio n
L inzenm eier ( 11-4)
s tu d ie d a s e r i e s o f s t i l l b o r n s an d two new borns, fo u r and f iv e days old#
The d u o tu s i n th e newborn t h a t had n o t b re a th e d was a lm o st a d i r e o t con­
t i n u a t i o n o f th e pulmonary a r t e r y , c o n i c a ll y ta p e r in g i n i t s o o u rse p o s­
t e r i o r l y t o th e l e f t , and a ro h in g s l i g h t l y l a t e r a l and i n f e r i o r l y t o
e n te r somewhat m e d ia lly i n t o th e a n t e r i o r w a ll o f th e d escen d in g a o r ta
-
a t a n a n g le o f ab o u t 3 0 °-4 0 °.
50 -
The p la c e o f e n tra n o e i s a b o u t 0*5 cm .,
below th e e n tra n o e o f th e l e f t su b c la v ia n a rte ry *
Bruitiltun elan Kladu, d u (M taet k*t
Fig. 2 a.
SehUaohmoieU, d u d » Dnkkalek nkUrM Mil.'
Fig* 18*
Linzenm eier*
Feldman ( ’ 20) d if f e r e d from th e fo re g o in g somewhat i n h i s d e s c r ip ­
t i o n o f th e d u o tu s .
A ooording t o him i t opened o b liq u e ly i n t o th e
a o r t a n e a r ly o p p o s ite to th e l e f t subolavia'n a r t e r y by means o f an
e l l i p t i c a l o p e n in g .
The a o r t i o w a ll in th e re g io n o f e n tra n o e o f th e
d u ctu s was r a i s e d in to r id g e s in s te a d o f b e in g smooth and was i n r e ­
l a t i o n t o th e vagus n e rv e .
G raper ( ’ 21) a l s o d e sc rib e d th e d u o tu s as
th e c o n tin u a tio n o f th e pulmonary a r t e r y bending backw ard t o open in to
th e d escending a o r t a a t an a n g le o f 30°-33° (R o e d e r).
The a o r t i o e n ­
tra n o e i s suoh t h a t th e duotus i s p la o ed on th e l e f t and a n t e r i o r s id e
o f th e a o r ta and i s a d h e re n t t o th e l a t e r a l s l i t- s h a p e d opened a o r t a .
The d u ctu s i s th e r e f o r e d e f i n i t e l y s e p a ra te d from th e a o r ta by a lo n g i­
t u d i n a l fu rrow b u t b o th th e duotus and a o r ta form a m u tu al w a ll a t th e
51
e n tra n c e and t h i s m i l a p p e a r as a v a lv e as p o s tu la te d by Strassm ann*
D ra g en d o rff ( ’29) d e s c rib e d th e a ro h o r th e a o r t a a s b e in g f l a t t e r
in th e newborn th a n i n l a t e r l i f e .
The pulmonary tr u n k and i t s d ir e o t
c o n tin u a tio n , th e d u o tu s , are p la c e d a g a i n s t th e a o r t i c a rc h in th e new­
b o rn .
I t i s o n ly a f t e r b i r t h t h a t th e r o o ts o f th e v e s s e ls a re r a i s e d ,
th e a o r t i c a ro h becomes h ig h e r and a g r e a te r space i s formed betw een th e
a o r t i c a ro h , th e pulm onary a r t e r y and th e d u ctu s a r t e r i o s u s .
ANOMALIES
The co u rse o f th e d u otus has been e x te n s iv e ly s tu d ie d , b u t i t s
an o m alies have n o t .
B i l l a r d (1839) d e s o rib e s th e case o f a newborn in
w hioh a s in g le h e a r t e x i s t e d , t h a t i s , only one a u r i c l e and one v e n tr io le
w ere p re s e n t and th e y communicated by means o f a la r g e f r e e foram en o a lle d
by him th e " t r i c u s p i d v a lv e " .
The pulm onary a r t e r y a ro se from th e ven­
t r i c l e a lm o st in im m ediate c o n n ec tio n w ith th e a o r ta and on i t s l e f t s id e
and th e n passed backw ards, g iv in g o f f th e two b ran ch es and c o n tin u in g a s
th e d u otus a r t e r i o s u s w hich was p e rv io u s and opened in to th e d esoending
a o rta .
The d u ctu s v a r ie d from th e norm al i n t h a t i t was " p e r f e c t l y im­
p e rv io u s a t i t s o r ig in from th e v e n t r i o l e betw een whioh and th e b if u r c a ­
t i o n was a p e r f e o t c u l - d - s a c ."
c i r c u l a t i o n a s fo llo w s :
Ilauran e x p la in s th e r e s u l t i n g change i n
"The blood having a r r iv e d a t th e v e n t r i c l e ,
was p r o p e lle d tow ards th e a o r t a , b u t , in s te a d o f coming to th e lu n g s
th ro u g h th e pulm onary a r t e r y , whioh was o b l i t e r a t e d n e a r th e h e a r t , th e
l e s s e r c i r c u l a t i o n was a f f e o te d i n d i r e c t l y by a re tro g r a d e c u r r e n t th ro u g h
th e d u ctu s a r t e r i o s u s , th e n ce i n t o th e pulmonary b ra n c h e s, to be re tu rn e d
t o th e v e n t r i c l e , th e common re o e p ta o le of t h i s an d o f th e b la c k blood o f
th e c a v a e ,"
T his ty p e o f r e v e r s a l o f b lo o d flow has formed th e b a s is o f
s e v e r a l t h e o r i e s o f change in c i r c u l a t i o n a t b i r t h and c lo s u r e o f th e
-5 2 -
d u c tu s a r te r io s u s *
tVrany (1871) l i s t s s e v e r a l o th e r ty p e s o f an o m alies o f th e duotus*
These anom alies can be su b d iv id e d in to s
1* A nom alies o f developm ent*
( a ) The ductus a r t e r i o s u s a r i s e s from th e r i g h t v e n t r i o l e and
e n te r s in to th e nonnal p la c e on th e a o r t a .
This ty p e
has been found b y H a lle r in a seven y e a r o ld fem ale c h ild
and in an a d u lt by W risberg*
(b ) The d u o tu s a r i s e s from th e l e f t pulmonary a r t e r y .
Examples
o f t h i s o o n d itio n were d e s c rib e d by S a n d ifo r t i n a seven
month o ld f e tu s an d i n th e a d u lt by Hoimnel*
(o ) The duotus a r i s e s from th e r i g h t pulmonary a r t e r y .
S ie b o ld
found t h i s in a c y a n o tic newborn and Krause in th e a d u l t .
(d ) The duotus may open i n t o a l e f t innom inate tru n k *
(e ) S itu s in v e rs u s may a l s o ocour*
II* A nom alies o f in v o lu tio n were a ls o d e so rib e d by ffirany, b u t th e s e
w i l l be d is c u s s e d s h o rtly *
POSTNATAL STRUCTURE OF THE DUCTUS ARTERIOSUS
The p o s tn a ta l o o n d itio n o f th e duotus h as been d e so rib e d f r e q u e n tly
in c l i n i c a l p a p e r s .
These d e s c r ip tio n s have been concerned p r im a r ily w ith
th e c l i n i c a l s ig n if ic a n c e o f i t s p e r s is te n c e and th e d egree o f i t s p a te n c y .
Langer (1857) how ever, d e so rib e d th e p o s tn a ta l d u ctu s a r t e r i o s u s from an
a n a to m ic a l p o in t o f v ie w .
th r e e days a f t e r b i r t h .
No n o tio e a b le change was observed i n th e d u c tu s
However, a t th e n in th day th e th io k e n in g o f
th e w a ll was w e ll advanced and th e in n e r s u rfa c e had become more
u n ev en .
The lo n g itu d in a l la y e r o f th e w a ll was e a s i l y d etach ed and
53-
beoame s t i l l t h i c k e r a t th e expense o f th e in n e r c a l i b e r of th e lumen
w hich th e r e f o r e became s t e a d i l y n arro w er due t o t h i s rid g in g o f th e w a ll*
Fig* 19*
Langer
The d uctus becomes shaped lik e a n hour g la s s w ith a rid g e form ing on th e
low er w a ll beoause o f i t s a rc h e d -sh a p e d course*
T his m iddle s t r i o t u r e
sp read s tow ard th e pulm onary end from f o u r te e n days onj th e narrow ed p a r t
becoming a s h o r t c a n a l e x te n d in g tow ard th e a o r t a , th e lumen becoming
s ta r -s h a p e d .
The t i s s u e c o n tin u e s t o become t h ic k e r and narrow s t o a
sm all r in g a t th e b e g in n in g o f th e c e n t r a l o p en in g .
fo rm atio n o f c o n n e c tiv e t i s s u e f i b e r s has b eg u n .
A t th r e e months th e
Among th e s e only s in g le
e l a s t i c f i b e r s a re found and th e s e a re u n ite d w ith th e a d v e n ti t ia o f th e
a o r ta and pulm onary a r t e r y .
T h is p ro g r e s s iv e developm ent o f th e embryonic
co n n ec tiv e t i s s u e t o f i b e r b u n d le s cau ses th e o u te r la y e r s o f th e duotus
to s h rin k so t h a t i t s o u te r d ia m e te r a t th r e e months i s no g r e a te r th a n
t h a t o f a " ra v e n * s -fe a th e r" (R a b e n fe d e rsp u le ) w h ile a goose q u i l l can
e a s i l y be p assed th ro u g h t h a t o f a new born.
o f la y e rs c e a s e s
By t h i s tim e th e a b s o rp tio n
and th e d e c re a se in le n g th o f th e d u o tu s has r e s u l t e d
-5 4 -
in p u llin g th e b i f u r c a t i o n o f th e pulm onary a r t e r y o lo s e r to th e a rc h o f
th e a o r t a .
The o u te r c o n to u r o f th e d u c tu s , how ever, i s s t i l l r e c o g n iz a b le .
L a te r in l i f e i t lo s e s i t s form and becomes lig a m e n to u s,
A v e ry f in e o an al
alw ays p a sse s th ro u g h th e c o n n e c tiv e t i s s u e s tra n d th ro u g h o u t l i f e .
T h is
c e n t r a l opening a r i s e s p r im a r ily a s a sm a ll opening from th e a o r t a ; fib r o u s
c o n n e c tiv e t i s s u e su rro u n d s i t s lumen and becomes c o n tin u o u s w ith th e
e l a s t i c f ib r o u s t i s s u e i n th e m edia o f th e a o r ta and pulm onary a r t e r y ,
Baumgarten (1877) d is c u s s e d th e f e t a l v e s s e ls and found t h a t th e
duotus sometimes rem ains open and c a r r i e s blo o d th ro u g h o u t l i f e .
T his
fr e q u e n tly o ccu rs when a p a th o lo g ic a l c o n d itio n o f th e h e a r t v a lv e s e x i s t s
a s i n s te n o s is o f th e m i t r a l o r a o r t i o o s t i a ,
Thama (1883) d i f f e r s w ith Langer in fin d in g t h a t d e f i n i t e changes
were n o tic e a b le in th e duotus a f t e r th r e e d ay s; th e s e changes s e t t i n g in
im m ediately a f t e r b i r t h .
Thoma d e s c rib e s i n th e th r e e day o ld newborn
" c e l l - r i c h " fo ld s w hioh l i e b e n e a th th e e n d o th e lia l la y e r s and form
rounded rid g e s a t th e a o r t i c e n tra n c e o f th e d u c tu s .
C o n tra c tio n o f th e
media g r e a t l y red u ces and narrow s th e lumen o f th e duotus cau sin g i t t o
become i r r e g u l a r and s ta r - s h a p e d .
The media c o n s it s m ain ly o f e l a s t i c o -
m uscular la y e r s betw een th e e l a s t i c a in tim a and en d o th eliu m .
These
t i s s u e m asses a re n o t g r e a t l y changed due t o c o n tr a c tio n , f o r i t i s
a f f e c te d a s i s th e m edia when c o n tr a c tio n o c cu rs and th e duotus changes
i t s form .
The f i b e r s a re i r r e g u l a r l y p la c e d and p a r t l y r a is e d tow ard
th e lumen, a n o tic e a b le a cc u m u la tio n o f homogeneous i n t e r c e l l u l a r sub­
s ta n c e ly in g on th e in n e r la y e r s o f th e r i d g e .
R eg ressiv e changes were o bserv ed in th e duotus in c h ild r e n ra n g in g
in age betw een t h i r t y - n i n e days and e ig h te e n m onths.
These changes were
55-
s im ila r t o a h y a lin e change o f th e m edia o f th e d u c tu s*
A new t i s s u e
fo rm a tio n le a d s t o a com plete o r a lm o st com plete c lo s u r e o f th e d uotus
w ith c o n n e c tiv e tis s u e *
Henle (1881) d e s c rib e s a f i b r o - e l a s t i c s tr a n d c o n ta in in g a f in e
m ic ro sco p ic lumen p re s e n t u n t i l l a t e i n l i f e .
T h is lumen was c a l l e d th e
" R e st lumen" by l a t e r i n v e s t ig a to r s w hich th ro u g h th e o b l i t e r a t i n g in tim a
(en d o th eliu m ) grow th i s in c o m p le te ly c lo se d *
Haberda (1896) was a b le t o p ass a "norm al probe" th ro u g h th e ductus
from th e pulm onary end i n s ix t o seven day o ld new borns.
A t n in e t o te n
days a f t e r b i r t h a two m illim e te r sound o n ly co u ld be p assed th ro u g h th e
pulm onary e n tra n c e o f th e duotus*
A t th r e e weeks th e lumen was s t i l l found
t o be p a te n t, a v e ry f in e sound o r t h i c k p i g ’s h a i r b r i s t l e c o u ld be
p a sse d th ro u g h .
A t s ix weeks th e d u o tu s was no lo n g e r p a te n t t o a b r i s t l e *
Kuschew (1901) found t h a t a c o n n e c tiv e t i s s u e grow th o c c u rs from th e
f i r s t day a f t e r b i r t h .
T his grow th does n o t e x te n d e q u a lly on t h e p e rip h e ry
o f th e duotus and th e r e f o r e d is p la c e s th e lumen t o an e c c e n tr ic p o s itio n *
T his co n n ec tiv e t i s s u e grow th does n o t d ev elo p e q u a lly th ro u g h o u t th e
le n g th o f th e lumen b u t m a in ly i n th e m id d le , b e in g much le s s developed
a t th e openings o f th e duotus*
The m uscle la y e r s w hich a r e com pressed
on t h e i r e x t e r i o r s by t h i s c o n n e c tiv e t i s s u e grow th a tro p h y and a re r e ­
p la c e d by c o n n e c tiv e t i s s u e .
The lumen o f th e d u c tu s w hich rem ain s m icro ­
s c o p ic a lly dem onstrable f o r a long tim e is v i s i b l e m ic ro s c o p ic a lly th ro u g h ­
out l i f e .
The s i t e o f th e p re v io u s c a n a l may be re p la c e d by c o n n e c tiv e
t i s s u e c o n ta in in g s p in d le -sh a p e d and round c e l l s , e l a s t i c t i s s u e and
v e s s e ls .
W ith t h i s grow th of th e c o n n e c tiv e t i s s u e o f th e in tim a th e r e
i s a n in c re a s e i n w eig h t o f th e a d v e n t i t i a and a c o rre sp o n d in g in c re a s e d
amount o f f a t t i s s u e , e l a s t i c and c o n n e c tiv e t i s s u e f ib e r s *
-5 6 -
Kuschew a g re e s w ith o th e r in v e s t i g a t o r s re g a rd in g th e c au ses o f
p a te n c y o f th e d u o tu s .
He does n o t a t t r i b u t e th e cau se t o throm bus
sin c e b u t 1.5?£ o f th e c ase s c o n ta in e d a throm bus and t h i s does n o t le a d
t o p aten o y o f th e d u c tu s .
K ir s te in ( f10) made tr a n s v e r s e s e c tio n s th ro u g h th e n a rro w e st p a r t
o f th e d u ctu s i n a te n day o ld in f a n t and found th e lumen s t i l l v i s i b l e
and e q u al in s iz e to t h a t o f a sm all o r medium a r t e r y .
A t fo u r t o f iv e
days th e duotus i s s t i l l open and no b lo c k in g o f t h e b lo o d flo w o c c u rs,
th u s c o n tr a d io tin g th e fin d in g s o f Thama.
show
The s e r i a l s e c tio n s o f K ir s te in
t h a t th e f i r s t grow th occunred a t f o r t y - f o u r c e n ti m e te r s , cro w n -h eel
le n g th , was n o tic e a b le i n th e newborn, and was n o tic e a b ly d ev elo p ed by
two weeks p o s t n a t a l .
S tie n o n ( ’ 12) found th e d uctu s perm eable up t o th e s i x t h day p o s t­
n a t a l and sometimes to th e tw e lf th day and even l a t e r .
The ligam entum
a r t e r i o s u n i n th e a d u lt i s o f v a r ia b le th ic k n e s s and c o n s is ts o f dense
c o n n e c tiv e t i s s u e e n clo se d by th e e l a s t i c t i s s u e o f th e rem ains o f th e
d u o tu s .
The rem ains o f th e lumen, are found i n th e c e n te r in th e form o f
v a c u o le s and narrow c ra c k s b u t th e places o f a o r t i c and pulm onary i n s e r tio n
a r e com pletdy c lo s e d o f f and show no t r a c e o f a c a n a l in norm al c o n d itio n s
o f developm ent.
two s ta g e s :
S tien o n th e r e f o r e d iv id e s th e c lo s in g o f th e d uotus in to
D uring th e f i r s t , i t i s a n a to m ic a lly open th ro u g h o u t i t s
le n g th a lth o u g h blood c an n o t p ass th ro u g h due t o d if f e r e n c e s in p r e s s u r e ;
d u rin g th e second, i t becomes th e s i t e o f s t r u c t u r a l tra n s fo rm a tio n s w hich
cause i t s d e f i n i t e c lo s u r e .
The s iz e o f t h e d u o tu s d im in ish e s v e ry q u io k ly ;
a t th e end o f tw e n ty -fo u r hours i t r e p r e s e n ts a narrow c a n a l a s compared
to th e l e f t pulmonary a r t e r y .
I t s le n g th a l s o d im in ish e s b ecau se i t a tta c h e s
-5 7 i t s e l f a g a i n s t , and u n ite s w ith , th e isth m u s o f th e a o r t a a t a b o u t i t s
m iddle*
S tie n o n t r e a t s a t same le n g th th e fo rm a tio n o f th e c i c a t r i c e s
( s c a r s ) t h a t t h e d u otus le a v e s in th e a o r t a and i n t h e pulm onary a r t e r y
when i t becomes tra n s fo rm e d i n t o th e ligam entum a r te r io s u m .
The c i c a ­
t r i c e s form ed a r e n o t s im ila r ; a t th e pulm onary end a l i g h t p u n c tifo rm
d e p re s s io n i s form ed w hich i s a lm o st r e g u la r l y rounded o f f ; w h ile a t th e
a o r t i o end th e s o a r o ccu p ies th e bottom o f a d e p re ss io n t h a t i s s e v e r a l
m illim e te r s d e ep .
The s o a r i s o f l i n e a r form , tr a n s v e r s e o r somewhat
o b liq u e , from two t o th r e e m illim e te r s long on th e a v e ra g e ; i t s u p p er l i p
o fte n more p r o je c tin g th a n th e lo w e r.
(See F ig , 7, page 2 1 ) ,
f a i n t e r w ith a g e , b u t n e v e r e n t i r e l y d is a p p e a rs ,
I t grows
(See F ig , 7, page 21)*
TUB PATENT DUCTUS ARTERIOSUS
B o ta llu s (1660) assumed t h a t th e d u ctu s was p a te n t f o r some tim e
a fte r b irth .
"B ut we f u r t h e r o b se rv e , t h a t th e p a ssa g es i n q u e s tio n a re
n o t o n ly p e rv io u s up t o th e p e rio d o f b i r t h i n man, a s w e ll a s i n o th e r
a n im a ls, a s a n a to m is ts i n g e n e ra l have d e sc rib e d them , b u t f o r s e v e r a l
months s u b s e q u e n tly , in scone ind eed f o r s e v e r a l y e a r s , n o t t o say f o r
th e whole c o u rse o f l i f e , "
B i l l a r d (1839) worked on a n e x te n s iv e s e r i e s o f new borns and found
t h a t i n o u t o f n in e te e n c h ild r e n one day o ld , th e d u ctu s i n t h i r t e e n was
f r e e and f i l l e d w ith b lo o d , i n fo u r o b l i t e r a t i o n had begun, and in two
was c o m p le te ly o b l i t e r a t e d .
In tw enty-tw o c h ild r e n o f two day p o s t n a t a l
t h i r t e e n d u c tu s w ere s t i l l open; i n s ix th e o b l i t e r a t i o n had begun and i n
th r e e th e o b l i t e r a t i o n p ro c e ss was co m p leted .
At th r e e days i n tw en ty -tw o
c ase s f i f t e e n w ere s t i l l open, i n f iv e o b l i t e r a t i o n began and was com-
-5 8 -
p l e t e d i n tw o .
I n tw e n ty -se v e n c h ild r e n a t fo u r days p o s tn a t a l se v e n te en
w ere s t i l l open, i n seven o b l i t e r a t i o n had begun and o n ly a sm a ll h o le
was l e f t w h ile th r e e were c o m p le te ly d o s e d .
I n tw e n ty -n in e c h ild r e n
a t f iv e days p o s tn a t a l th e duotus was s t i l l open i n f i f t e e n .
Of th e s e
f i f t e e n , th e d u c tu s was v e ry la r g e in ten ^an d in f iv e th e o b l i t e r a t i o n
had begun and was q u ite advanoed.
In seven th e o b l i t e r a t i o n was a lm o st
c o m p le te , m e re ly a narrow h o le re m a in in g .
c o m p le te .
In seven th e o b l i t e r a t i o n was
In tw e n ty o h ild r e n a t e ig h t days th e d u c tu s was s t i l l open in
t h r e e , one c o n ta in in g a n aneurysm o f th e d u c tu s; s i x were a lm o s t e n t i r e l y
o b l i t e r a t e d and e le v e n were c o m p le tely o b l i t e r a t e d .
The d u ctu s may s t i l l
be open a t 12-15 days and i n t o th e t h i r d week b u t i t i s u s u a ll y c lo s e d on
th e e ig h th o r t e n t h day,
R ok itan sk y (1844) d is c u s s e s th e d u ctu s in h i6 p a th o lo g ic a l s tu d ie s
and assum es t h a t th e p a te n c y o f th e d u ctu s in v o lv e s a c o rre sp o n d in g p aten o y
o f th e foram en o v a le .
In some c a se s i n w hich th e r e i s an e x p a n sio n o f th e
a o r t i o end o f th e d u ctu s from th e d i r e c t i o n o f th e a o r ta tow ard th e d u ctu s
i t i s p ro b a b le t h a t th e b lo o d flow s from th e a o r ta tow ards th e pulm onary
a r t e r y and in such c ase s th e tra n s m is s io n o f th e blo o d of th e r i g h t a t r i a ,
and th e p a te n c y o f th e foram en o v a le , a r e th e r e s u l t o f th e e x c e s s iv e
f u l l n e s s o f th e duotus due t o th e p assag e o f a o r t i c blood in to th e p u l­
monary a r t e r y and th e consequen t o b s tr u c tio n to a f r e e d isc h a rg e o f blood
from th e r i g h t s id e o f th e h e a r t ,
Chevors (1845) a g re e s w ith R o k itan sk y t h a t perm anent p a te n c y o f th e
d u ctu s may be due t o
th e e x is te n c e o f an impedim ent to th e c o u rse
o f c i r c u l a t i o n o f th e f e tu s w hich p re v e n ts o lo su re a f t e r b i r t h .
E a rly
p o s tn a t a l o b s tr u c tio n w i l l have th e same e f f e c t a s w i l l f a i l u r e o f th e
-5 9 -
p ro c e sse s c a u s in g c lo s u re *
The d u ctu s b e g in s t o o o n tra c t s h o r tly a f t e r
th e commencement o f r e s p i r a t i o n and i s c lo se d
w ith in s ix
to tw e lv e days*
I f i t rem ains open th e blo o d may flo w d i r e c t l y from th e pulm onary a r t e r y
t o th e a o r t a o r in th e r e v e rs e d i r e c t i o n , th u s p la c in g an undue lo ad upon
th e r i g h t v e n tr ic le *
V a rio u s d e g re e s o f c o n tr a c tio n occur*
A t tim es
com plete o b l i t e r a t i o n o f th e upper p a r t o f th e d escending th o r a c ic a o r t a
i s observed i n c o n n e c tio n w ith a p erm an en tly open s t a t e o f th e d u o tu s; a
s im ila r n arro w in g a ls o e x is t * when
th e c a n a l (d u c tu s )
i s c lo s e d .
The
a o r ta may be found e i t h e r c o n tra c te d o r q u ite occluded a s h o r t d is ta n c e
above or im m ed iately below th e d u c tu s ; in th e s e o ases th e c a n a l i s con­
t r a c t e d f o r a s h o r t d is ta n c e , o r a r a is e d fa lc if o r m p ro o e ss ex ten d s p a r ­
t i a l l y a c r o s s i t , o r i t is c lo s e d a b r u p tly a s
a t h i n c o rd .
though i t were t i e d w ith
These changes were g e n e r a lly unaccompanied by any p u c k e rin g ,
roughening o r o th e r t r a c e o f in flam m ato ry a c ti o n - " th e se forms o f narrow ­
in g and o b l i t e r a t i o n n e v e r occur in an y o th e r p o r tio n o f th e a o r ta e x ce p t
t h a t which i s c lo s e ly a d ja c e n t t o th e c a n a lis a r te r io s u s * "
K lo tz ( '0 7 ) on th e o th e r hand found th e ductus p r a c t i c a l l y fu n o tio n l e s s a f t e r th e f i r s t hour o r so a f t e r b i r t h and a t t r i b u t e s t h i s to e i t h e r
a re d u c tio n i n blood p r e s s u r e o r t o m u scu lar c o n tr a c tio n o f i t s w a lls*
Pohlman ( '0 9 ) assum es t h a t th e c o n tin u e d p aten o y o f th e duotus i s
o lo s e ly dependent upon th e foram en o v a le rem aining f u n c tio n a lly p a te n t .
The duotus c an n o t rem ain f u n c tio n a lly p a te n t i f th e foramen o v ale i s
c lo se d and th e v e n t r i o u l a r septum i s i n t a c t u n le s s th e r e i s a trem endous
com pensation i n th e b ro n c h ia l c i r c u l a t i o n or a r e l a t i v e l y g r e a te r f u n c tio n ­
a l c a p a o ity o f th e r i g h t v e n t r i c l e a s in c o ld blooded anim als*
-6 0 -
TlhE OF POSTNATAL CLOSURE
Gundobin ( ’12) in h i s s tu d ie s o f th e anatomy o f th e i n f a n t found
t h a t i n a s e r i e s c o n s is tin g o f f o r t y o a se s th e duotus i n e ig h te e n was
c lo se d betw een
t h i r t y and s ix t y days a f t e r b i r t h and t h a t a f t e r fo u r
months th e d u ctu s was c lo s e d i n
a ll*
d ra p e r ( ’ 21) found t h a t th e lumen rem ained open f o r two t o th r e e
d a y s.
A ocording t o L anger, th e d uotus r e t a i n s a sm all lumen f o r more
th a n fo u r te e n days a f t e r b i r t h .
E ls a s s e r s t a t e s t h a t th e b e g in n in g and
ending o f c lo s u r e o o c u rre d d u rin g th e f i r s t s ix weeks a f t e r b ir th *
G erard however
assumes t h a t th e p ro o e s se s o f c lo s u r e occur d u rin g th e
p e rio d ran g in g
from f o u r te e n t o tw en ty days p o s tn a ta l*
In th r e e oases
th e d u ctu s rem ained open betw een s i x and tw e n ty -fo u r months*
A lvarengo
de C osta (1869) found th e duotus c lo s e d a f t e r two m onths, and alw ays a f t e r
th r e e to fo u r months*
Haberda found t h a t th e g r e a t e r number were c lo se d
a f t e r s ix weeks and alw ays a f t e r s ix months*
Llelka on th e o th e r hand
found t h a t th e p e rio d o f c lo s u r e was more le n g th y - c lo s u re o co u rred a f t e r
f iv e months and a n i r r e g u l a r c r e s c e n t shaped lumen rem ained u n t i l a s l a t e
a s te n months p o s tn a ta l*
l a t e r or n o t a t a l l *
A f te r t h a t tim e i r r e g u l a r c lo s u re o c c u rre d s t i l l
Vfeizmann (*11) found a lumen s t i l l d is o e r n ib le u n t i l
e ig h ty y e a rs o f a g e , b u t t h i s lumen was n o t u n ite d w ith t h a t o f th e
pulm onary a r t e r y and o f th e a o r t a .
A ocording t o Melka a sm all s p l i t
e x is te d a t two months w hich was somewhat w id e r th a n t h a t a t f iv e months
or in th e a d u lt where i t e x is t e d a t th e pulm onary end o n ly .
P a tte n found
t h a t th e d u ctu s g ra d u a lly d e c re a se s i n d ia m e te r d u rin g th e f i r s t p o s t­
n a t a l month and th e lumen i s alm o st c o m p le tely c lo s e d by fo u r o r f iv e
w eeks.
A ccording t o him com plete o b l i t e r a t i o n ooours s ix t o e ig h t weeks
-6 1 -
a f t e r b ir th *
Soammon and l'Jo rris ( ’18) com piled d a ta on th e tim e o f p o s tn a ta l
o b l i t e r a t i o n o f th e d uotus a r t e r i o s u s and found t h a t th e tim e o f i t s
o lo s u re o c c u rre d laterm s thm commonly b e lie v e d *
Ih e p e rc e n ta g e o f
c lo s u re o f th e duotus was l e s s th a n t h a t o f th e foram en o v a le a t a
Da ta im the fr e q u e n c y o f pout-natal nhlitc ia tn> n«f the Ituetua artcrioeus.
sm do sc d i n parcnthv.se* i n dn ate u u tu lu r a t ah h t c r a t a t conee
I I D I I I V U AND UATI
I!i
5 I<
: j9
i
1 i
111 II
AlvrroiiRii,
B m m t/.
Numerate 1
ii‘i
2
Hill ard . ' H
KUhs ki t.
."iJ .
I,
I''
Fig* 20*
co rre sp o n d in g p e rio d *
|M
11
Soammon & N o rris
The r a t e o f o b l i t e r a t i o n was v e ry r a p id from
th e f o u r th week to th e end o f th e t h i r d month and n e a r ly 95% o f th e
duotus were c o m p le te ly o b l i t e r a t e d by th e end o f th e f i r s t y e a r .
The
p e rio d s o f c lo s u re o r o b l i t e r a t i o n co u ld be d iv id e d in to th r e e p e rio d s 1* The i n i t i a l p e rio d when th e r a t e o f o b l i t e r a t i o n was low*
2 . The m iddle p e rio d d u rin g w hich th e r a t e r i s e s and th e m a jo rity
o f c a s e s a re c lo se d *
3* The te rm in a l p e rio d when th e r a t e a g a in becomes slow er*
-6 2 -
/
F ig . 21.
Soammon & N o rris
The r a t e o f o b l i t e r a t i o n of th e d uotus i s somewhat slo w er th a n t h a t o f
th e duotus v e n o su s.
The maximum r a t e o f c lo s u r e o f th e d u o tu s i s a t ­
ta in e d a t two m onths, th r e e - q u a r t e r s o f a l l th e o a se s a r e c lo se d by th e
end o f th r e e months and 95%> a r e c lo s e d by th e end o f th e f i r s t y e a r .
.4
r<iit
hi
•i ‘i • ! ,
!ih i
1st W r r k
I week
lo
1 ni"iith
J n i ! ni'iutli
3 r d TM-' iit It
3 t o ti m o n t h ?
t> t o 12 m o n t h s
1 t o .» v m i r s
F ig . 2 3 .
3*6 moa
6M2moe
Hg, 3
I'lireo c u r v e s s h o w i n g t h e a p p r o x i m a t e a v e r a g e d a i l y r a t e o f o b l i t e r a - |
t i o n o f ihi! fe ta l b l o o d -p a s s a g e s in c u r ly life
.4, d o t t e d line, f o r a m e n o v a l e , :
H, Holiil line, d u c t u s a r t e r i o s u s ; C b r o k e n line, d u c t u a v en o s u s . B a s e d U|>on 1
t h e d a t a n u m u m r i z e d in t a b l e 0
F ig . 22.
Soammon & N orris
Soammon & N o rris
-6 3 -
S trassm ann (1894) a tte m p te d t o i n j e o t th e p o s tn a t a l human duotus
and found t h a t i t could he f i l l e d when in je c t e d from th e abdom inal
%
a o r t a a f t e r t h i r t y - s i x and s ix ty - n in e h o u rs j th e a o r t i c end however was
l e s s f i l l e d th a n th e pulm onary en d .
The d uotus c o u ld s t i l l be i n je c te d
from th e pulm onary a r t e r y th u s d is p ro v in g th e c o n te n tio n o f Schanz t h a t
i t c o u ld n o t be in je o te d .
In th e dog, th e d u ctu s c o u ld n o t be in je c te d
from th e a o r ta a f t e r tw elve t o f i f t e e n d a y s.
I t was p o s s ib le t o i n j e o t
th e duotus i n th e human from e i t h e r th e a o r t i c o r pulm onary end up to th e
end o f th e s i x t h month and up to th e b e g in n in g o f th e se v e n th m onth.
C h r is tie (*30) ta b u la te d h is o b s e rv a tio n s on th e tim e o f c lo s u r e o f
f iv e hundred and f i f t y - e i g h t ductus i n in f a n t s ra n g in g from one day t o one
y e a r o f a g e, and p lo tte d th e fo llo w in g cu rv e whioh shows a r a p id and u n i­
form tim e o f c lo s u r e up t o ab o u t e ig h t weeks and th e n a marked slow ing and
d e v ia tio n in th e course of th e o u rv e .
E i g h ty - e ig h t p e rc e n t o f th e f iv e
hundred and f i f t y - e i g h t in f a n ts showed a c lo s e d d u c tu s a t e ig h t w eeks.
T h is i s somewhat l a t e r th a n th e tim e s t a t e d i n G ray’ s Anatomy w hich i s
fo u r t o t e n d a y s.
j
100
J
72
2 Whs. . . . . 64.7
. . . . 21.0
l »
0
4052
40 52
TYme in w eeks
C hart 2.—N orm al closing time o f the ductus arteriosus in 558 normal hearts
o f infants from 1 day to 1 year o f age.
F ig . 2 4 .
C h r istie
-6 4 -
LiEASUEEMENTS
Many in v e s t i g a t o r s s tu d ie d n o t o n ly th e s tr u o tu r e and m o rp h o lo g io al
ohanges o f th e d u o tu s, b u t a l s o made m easurem ents o f i t i n an a tte m p t to
c o r r e l a t e i t s s iz e w ith i t s s t a t e o f developm ent.
Many, how ever, f a i l e d
to ta k e i n t o c o n s id e r a tio n th e s iz e o f th e c h e s t and i t s changes a t d i f ­
f e r e n t p e rio d s and th e p o s s ib le e f f e c t s upon th e d u o tu s .
Roys ( '2 2 )
s tu d ie d th e changes in form and s iz e o f th e th o ra x in th e human f e tu s
and found t h a t v e ry m arked changes o co u rred i n th e a n t e r i o r c h e s t w a ll
d u rin g embryonic l i f e and th e s e ohanges were dependent p r im a r ily upon
m o d if ic a tio n s i n form and r e l a t i o n s o f th e th o r a c ic and u p p er abdom inal
v is c e r a suoh a s th e h e a r t and l i v e r .
D uring th e f e t a l p e rio d th e a n t e r i o r
re g io n o f th e th o ra x in c r e a s e s in s iz e b u t th e g e n e ra l form te n d s t o r e ­
m ain c o n s ta n t.
D uring e a r l y p r e n a ta l l i f e th e th o r a c ic in d ex i s v e ry h ig h
due t o th e g r e a t a n te r o - p o s te r io r d iam eter o f th e h e a r t and l i v e r b u t w ith
developm ent o f th e c a r tila g in o u s th o ra x th e th o r a c ic in d e x drops r a p i d l y .
A f te r th e second month th e c h e s t a p p ea rs o ir o u l a r i n c ro s s s e c t i o n , or
s lig h tly f la tte n e d a n te ro -p o s te rio rly .
T his " c y l i n d r i c a l " ty p e o f th o ra x
i s c h a r a c t e r i s t i c o f v a rio u s anim als and human f e t u s e s .
A cco rd in g t o th e
fin d in g s o f Roys th e th o r a c ic index i s a p p a r e n tly o lo s e ly a s s o c ia te d w ith
th e h a b its and l i f e o f th e a n im a l.
I have been u n a b le to f in d re fe re n c e
in th e l i t e r a t u r e o f any a tte m p t to c o r r e l a t e th e s i z e , shape o r th o r a c ic
in d ex o f th e th o ra x or th o r a c ic s t r u c t u r e s w ith th e s iz e o r shape o f th e
d u c tu s •
K ilia n (1826) d id n o t c o n sid e r th e d u ctu s a s a b ran ch o f th e p u l­
monary a r t e r y because o f i t s s i z e .
He assumed t h a t th e pulm onary a r t e r y
and ductus were th e same v e s s e l; in th e fo u r to s i x week o ld embryo th e
-6 5 -
d u c tu s was seven to n in e li n e s ( l i n i e n ) .
In th e newborn of a few days
th e pulm onary a r t e r y and a o r ta was o f th e same s i z e .
In th e f u l l y de­
velo p ed f e t u s th e le n g th from th e h e a r t t o th e a o r ta was one in c h ( i n ­
c lu d in g th e pulm onary a r t e r y ) and th e d iam eter o f th e lumen e q u al t o a
q u i l l ( f e a t h e r ) and s u b je o t to a g r e a t d eal o f v a r i a t i o n .
There i s a
d e c re a se i n th e d iam eter where th e d u ctu s e n te r s th e d escen d in g a o r ta j
t h i s d e o re a se o c c u rrin g tow ard th e end o f p reg n an cy so t h a t th e d iam eter
f a l l s in to th e r a t i o o f 43:41 or 40 in p ro p o rtio n t o th e a o r ta w hich i s
37.
There i s a narrow ing o f th e lumen o f th e a o r t a th r e e t o fo u r " li n ie n "
d i s t a l t o th e o r ig i n o f th e su b c la v ia n a r t e r y end th e n th e a o r t a w idens
a g a in a f t e r re c e iv in g th e d u c tu s .
T h is o o n d itio n can be re c o g n iz e d from
th e f o u r th f e t a l month onward.
Itiw isch (1851) a ls o found t h a t th e d u ctu s and pulm onary a r t e r y were
o f a lm o st th e same s i z e .
The le n g th o f th e d u ctu s and pulm onary a r t e r y
in th e newborn was seven m illim e te r s ; th e c irc u m fe re n c e of th e duotus
e ig h t m illim e te r s and t h a t o f th e pulmonary a r t e r y e le v e n m i lli m e t e r s .
The a o r ta m easured s ix and o n e -h a lf m illim e te r s i n c irc u m fe re n ce above
th e e n tra n c e o f th e d u ctu s and seven and o n e -h a lf m illim e te r s in circum ­
fe re n c e below th e e n tra n c e o f th e d u o tu s .
P e a sle e (1854) d id n o t f in d t h a t th e pulm onary a r t e r y and th e a o r ta
were o f s im ila r s i z e .
In a fo e tu s s i x months o ld th e sem i-circu m feren c e
o f th e pulm onary a r t e r y was .12 in c h and t h a t o f th e duotus .0 4 in c h .
In a f e tu s e ig h t and o n e - h a lf months o ld th e sem i-circu m feren o e of the
pulm onary a r t e r y was .25 in c h and t h a t o f th e d u c tu s .08 in c h , th u s
showing th at th e duotus 'was p e r c e p tib ly s m a lle r th a n th e pulm onary a r t e r y .
The d uotus ta p e r e d tow ard i t s a o r t i c end i n th e o ld e r f e tu s and was t h e r e -
-6 6 -
f o r e somewhat s m a lle r a t i t s u n io n w ith th e desoending aorta*
W alkoff (1868) m easured th e duotus and found i t t o be one and oneq u a r te r c e n tim e te rs in le n g th and th e d iam eter o f th e lumen f iv e t o
s i x m illim e te r s *
Wrany*3 (1871) m easurem ents a g re e c l o s e l y w ith th o s e o f W alkoff in
t h a t th e le n g th m easured one t o one and f i v e - t e n t h s c e n tim e te rs and i n
r a r e o a se s from two t o fo u r c e n tim e te rs and th e th ic k n e s s f iv e m i l l i m e te rs j th e lumen b e in g wide enough to aooommodate a goose q u i l l *
Thama
(1883) m easured th e m iddle d ia m e te rs o f th e pulmonary a r t e r y i n th e new­
b o rn and found i t to be n in e m illim e te r s a s compared to 8 .2 m illi m e t e r s
in th e ascen d in g a o r t a ,
n e tte n h e im e r (1894) o b ta in e d a m easurem ent o f
6*8 m illim e te r s f o r th e m iddle d iam eter o f th e duotus in th e f u l l term
f e tu s and 4 m illim e te r s in th e pulmonary a r t e r i e s .
Kusohew ( '0 1 ) s tu d ie d
an e x te n s iv e s e r i e s o f 205 i n f a n t cad av ers and found t h a t th e d u c tu s a ro se
from th e b i f u r c a t i o n o f th e pulm onary a r t e r y in 92.8>o o f th e c a s e s and
opened on th e i n f e r i o r vra.ll o f th e a o r t i c a r c h .
7 .1 m illim e te r s and i t s d ia m e ter 3 .9 m ill i m e t e r s .
I t s av erag e le n g th was
I t r e t a i n s th e same
s iz e to a b o u t s ix months and th e n e n la rg e s to re a ch a maximum i n th e a d u l t .
T h is i s n o t i n agreem ent w ith th e fin d in g s o f o th e r i n v e s t i g a t o r s .
Feldman q u otes from Kuschew th e le n g th o f th e ductus in th e newborn a s
6 .9 m illim e te r s and i t s d ia m e ter 4 .3 m il li m e t e r s .
A f te r seven days i t s
s iz e ohanges to 6 .2 m illim e te r s i n le n g th and th re e m illim e te r s i n d ia m e te r.
A fte r one y e a r i t s le n g th i s 6 .8 m illim e te r s and i t s d ia m e te r s t i l l th r e e
m illi m e t e r s .
A f te r tw e n ty -fiv e y e a rs i t s le n g th ha3 in c re a s e d t o 9 .6
m illim e te r s and i t s d ia m e ter to 5 .8 m i lli m e t e r s .
V ie r o r d t (*06) g iv e s
s e v e r a l t a b l e s o f m easurem ents f o r th e b eg in n in g o f th e g r e a t v e s s e l s .
-6 7 -
Ih e m iddle d ia m e te r o f th e newborn pulmonary a r t e r y m easured 2 3 .5 m i l l i ­
m e te rs and th e a sc e n d in g a o r t a 18 m ill i m e t e r s .
Feldman ( ’ 20) q u o te s th e
m easurem ents o f B iz s t and P i l l i e t , who found t h a t th e lumen o f a r t e r i e s
in c re a s e w ith th e grow th o f th e body.
The lumen o f th e pulm onary a r t e r y
was found t o be l a r g e r th a n t h a t o f th e a o r ta in th e f e tu s o f seven
m onths; th e m easurem ents in th e m ale b e in g 1 .5 o e n tim e te rs and 1 .4 c e n t i ­
m e te r s .
In th e newborns th e m easurem ents a re 2 .4 and 2 o e n tim e te r s .
There i s a c o n s ta n t d if f e r e n c e o f betw een 0 .2 and 0 .4 o e n tim e te rs u n t i l
s ix te e n y e a rs o f age betw een th e pulm onary a r t e r y and a o r t a , th e m easure­
m ents b ein g g r e a t e r i n th e m ale th a n i n th e fe m a le .
B e ttin g e r ( ’ 32)
m easured th e a sc e n d in g a o r ta and found i t t o be 1 4 .4 m illim e te r s lo n g ,
and n arro w in g somewhat below th e o r i g i n o f th e l e f t s u b c la v ia n a r t e r y .
The a o r ta w idens a g a in a t th e b e g in n in g o f th e d escen d in g a o r ta t o
m easure f i f t e e n m illi m e t e r s .
w id e n in g .
The duotus opens in to th e b e g in n in g o f t h i s
The le n g th o f th e duotus m easured 10,9 m illim e te r s and i t s
d ia m e ter a t th e a o rtic end 7 .9 m ill i m e t e r s .
These re c o rd e d m easurem ents, a lth o u g h num erous, a re n o t in c lo s e
agreem ent beoause o f th e v a rio u s ty p e s o f m easurem ents made and d i f f e r e n t
o r it e r i a used.
S ince th e v e s s e ls in v o lv e d a re q u ite sm all and a g r e a t
d e a l o f lo o se c o n n e c tiv e t i s s u e and f a t su rro u n d s them i t i s
v e ry d i f f i c u l t t o c a r e f u l l y c le a n away th e
t h a t a o o u ra te m easurem ents can be m ade.
t i s s u e from th e s e v e s s e ls so
These m easurem ents may th e r e f o r e
o n ly be c o n sid e re d a s a more o r le s s g e n e ra l i n d i c a tio n o f th e com parative
s iz e s o f th e s t r u c t u r e s and th e ohanges i n s iz e s a t d i f f e r e n t p e rio d s o f
developm ent o r grow th.
M a te ria l o f s i m i l a r age or degree o f p h y s io lo g ic a l
developm ent has n o t been u sed th ro u g h o u t th e se s t u d i e s .
T h is has r e s u l t e d
-6 8 -
in m arked v a r ia tio n s *
"RIDGE” . 11VALVE” . OR FOLD OF DUCTUS ARTERIOSUS
Marked d if f e r e n c e s o f o p in io n and o f d e s c r ip ti o n o f th e i n t e r n a l
s tr u o tu r e o f th e d u otus a r e found in th e l i t e r a t u r e #
Some i n v e s t i g a ­
t o r s have d e s c rib e d th e in n e r s u rfa c e o r lumen o f th e duotus a s b e in g
sm ooth, o th e rs a s b e in g smooth d u rin g p r e n a t a l l i f e and changing t o a
puckered c o n d itio n p o s t n a t a l l y .
S e v e ra l have d e s c rib e d th e e x is te n c e
o f a lo n g itu d in a l rid g e o r f o ld o r s e v e ra l rid g e s or fo ld s w ith in th e
d u ctu s and have a tte m p te d to e x p la in th e o r ig i n and s tr u o tu r e o f th e s e
fo ld s or r i d g e s .
They have been p la c e d by same a t th e a o r t i c end o f th e
d uotus and a t th e pulm onary end by o t h e r s .
Some in v e s t ig a t o r s have ex­
p la in e d th e s e rid g e s o r f o ld s a s b e in g v a lv u la r in fu n c tio n and o th e rs
have a.ssumed t h a t th e y m e re ly a ro s e due t o a k in k in g , bending o r t w i s t ­
ing o f th e d uotus w ith th e o n s e t o f r e s p i r a t i o n .
These r id g e s o r fo ld s
have a ls o been made th e b a s is o f s e v e ra l th e o r ie s a tte m p tin g t o e x p la in
th e c lo s u r e of th e ductus*
C arcanus (1754) and B ernard (1733) knew o f th e e x is te n c e o f a p ro ­
j e c t i o n in th e d u c tu s .
Z w e ife l quoted by Strassm ann a ls o o b serv ed t h a t
a rid g e e x is te d i n th e d u c tu s and assumed t h a t i t a c te d a s a v a lv e t o
p re v e n t th e backflow o f b lo o d i n t o th e d uotus w ith in c re a s in g blo o d
p re ssu re .
K ilia n (1826) s e c tio n e d th e d uotus l o n g i tu d in a lly and d e s­
c rib e d i t a s an u n in te r r u p te d c a n a l c o n ta in in g no v a lv e s or p r o je c tio n s
and t h a t i t was o f uniform th io k n e s s s im ila r t o th e w a ll o f an a r te r y *
Langer d e s c rib e s th e h is to lo g y o f th e d u o tu s in th e f u ll te r m s t i l l b o r n
and found t h a t th e d u ctu s la o k s a com pact, formed la y e r o f e l a s t i c f i b e r s
in th e w a ll*
The a d v e n t i t i a c o n ta in s f i n e , lo o s e ly in terw o v en f i b e r s ;
th e m edia has th e same s t r u c t u r e and a l s o tr a n s v e r s e t h i c k d e p o s its o f
o e l l s p e n e tr a ti n g th e is la n d s o f l o n g itu d in a lly ru n n in g o e l l s tra n d s
tow ard th e in n e r s u r f a c e .
The w a lls o f th e duotus a r e s tro n g e r th a n those o f
th e pulm onary a r t e r y and a o r t a .
A th io lcen in g o f one s id e o f th e d u ctu s
i s form ed by numerous lo n g itu d in a l o e l l s tr a n d s p e n e tr a tin g th ro u g h th e
m edia th u s form ing a marked c e l l u l a r grow th on th e in n e r s u r f a c e .
T h is
grow th a p p e a rs a s a bundle shaped p r o je c tio n on th e in n e r s u rfa c e so
t h a t th e d uotus h a s l o s t i t s sm oothness and shows lo n g itu d in a lly ru n n in g
rid g e s whose
form
resem b les broken down fib r o u s t i s s u e .
Langer ob­
se rv e d no n o tic e a b le change i n th e d u o tu s d u rin g th e f i r s t th re e days
b u t by th e n in th day th e th ic k e n in g o f th e w a ll was w e ll advanced, th e
in n e r su rfa o e becoming u neven.
The f i b e r s o f th e w a ll were s o f t and
e a s i l y s e p a ra te d ; th e lo n g itu d in a l l a y e r was e a s i l y d etach ed and became
s t i l l th io k e r th u s ta k in g up p a r t o f th e lum en.
A p ro g re s s iv e narrow ing
o f th e v e s s e l th u s ooourred th ro u g h t h i s lo n g itu d in a l rid g in g o f th e w a l l .
The rid g e was g r e a t e s t i n th e m iddle o f th e v e s s e l i n th e fo u r te e n day
o ld o h i l d .
(See F ig . 19, page 5 3 ).
T ra n sv e rse s e o tio n s ta k e n from th e
m iddle o f th e d u o tu s show o i r c u l a r la y e r s o f c o n n e c tiv e t i s s u e su rro u n d ed
on th e p e rip h e ry by a w h ite r i n g o f m edia and a d v e n t i t i a .
The lumen o f
th e m iddle t h i r d o f th e d u otus i s la rg e enough to p e rm it th e p assag e o f
a n e e d le and a s th e pulm onary and a o r t i c ends a re approaohed t h i s c e n t r a l
lumen in c r e a s e s i n s i z e .
The d u ctu s i s o o n s tr ic te d i n i t s m iddle and
th e r e f o r e shaped l i k e an "hour g l a s s " .
S ince th e o o u rse d e sc rib e d by
th e d uctus i s t h a t o f an a r c , th e p o s t e r i o r w a ll i s s h o r te r th a n th e
a n t e r i o r w a ll.
s iz e and sh a p e .
The rid g e o f th e w a ll c an n o t th e r e f o r e be o f uniform
A f te r f o u r te e n days th e m iddle s t r i c t u r e o f th e d u ctu s
-7 0 -
o o n tin u e s t o sp re a d tow ard th e pulm onary end so t h a t t h i s narrow ed p a r t
beoomes a s h o r t o a n a l t h a t p ro g re s s e s tow ard th e a o r t a .
t h i s s h o r t o a n a l o f th e d uotus i s " s t a r - s h a p e d " .
The lumen o f
The p r o l i f e r a t i o n o f
t i s s u e re d u c es th e b e g in n in g of th e o e n tr a l lumen to a s m a lle r c a l i b e r .
Since th e c o u rse o f t h e duotus i s o b liq u e , t h i s " o re so e n t-sh a p e d ” p ro ­
j e c t i o n o r rid g e l i e s a g a in s t th e a o r t a a n t e r i o r l y and a g a in s t th e r i g h t
b ranch o f th e pulm onary a r t e r y p o s t e r i o r l y .
He sa y s , " t h a t t h i s rid g e
does n o t fu n c tio n a s a v alv e i s e v id e n t."
W alkoff a g re e s w ith la n g e r in t h a t th e s e lo n g itu d in a l r id g e s a re m ost
marked in th e m iddle o f th e d u o tu s .
A grow th m ain ly o f th e in tim a o o o u rs,
i t s endothelium and s p in d le -s h a p e d elem en ts growing i n t o th e lumen o f th e
d u o tu s .
The fo rm a tio n o f w h ite and e l a s t i o c o n n e c tiv e
t i s s u e o ccu rs in
th e m ed ia.
Thama found t h a t a th ic k e n in g o ccu rs i n th e th r e e day o ld i n t e r n a l t o
th e e n d o th e lia l l a y e r s .
These " o e l l - r i c h " la y e r s form rounded r id g e s a t
th e a o r t i c e n tra n c e o f th e d u c tu s whioh th ro u g h c o n tr a c tio n o f th e media
g r e a t l y red u ces and narrow s th e lumen o f th e d u o tu s.
The f i b e r s o f th e
media a re i r r e g u l a r l y a rra n g e d and s l i g h t l y p ro je o te d i n t o th e lum en.
A
n o tic e a b le a cc u m u la tio n o f homogeneous i n t e r c e l l u l a r su b stan o e i s d i s ­
p e rsed upon th e in n e r la y e r s o f th e r i d g e .
Sohanz (1889) s e c tio n e d th e d uotus lo n g it u d in a ll y and found a number
o f fo ld s on i t s in n e r s u rfa o e w hich he m a in ta in e d had n o t been p re v io u s ly
d e s c rib e d .
His te c h n iq u e in v o lv e d i n f l a t i n g th e lu n g , a llo w in g i t t o
s ta n d f o r same tim e and th e n s e c tio n in g th e d uotus lo n g i t u d i n a l l y .
He
th o u g h t t h a t th e fo rm a tio n o f th e s e f o ld s m ig h t be due i n seme manner to
th e i n f l a t i o n o f th e lu n g s .
He a ls o exam ined a s ix month o ld f e tu s b u t
-7 1 -
found no f o ld s i n th e in tim a .
In th e e i g h t t o f o u r te e n day o ld c h i l d
th e d uotus had become shaped l i k e a n h o u r- g la s s b u t c o n ta in e d no t r a n s ­
v e rs e r id g e s ; lo n g itu d in a l f o l d s , how ever, w ere n o tic e a b le .
He e x ­
p la in e d th e fo rm a tio n o f th e s e lo n g itu d in a l f o ld s b y assum ing t h a t th e
e l a s t i c la y e r s a r e a rra n g e d t r a n s v e r s e l y i n th e s t i l l b o r n and l a t e r b e ­
come lo n g i t u d i n a l , th u s g iv in g r i s e t o th e s e lo n g itu d in a l r i d g e s .
G erard (1900) d e s c rib e d numerous la y e r s o f smooth m usole c e l l s in
th e meshes o f th e n etw orks o f e l a s t i c and c o lla g e n o u s c o n n e c tiv e t i s s u e
t h a t a re e x te r n a l t o th e e l a s t i o a i n t e r n a .
A f te r th e f i r s t few days
p o s tn a ta l th e e l a s t i c in tim a grows i n th e form o f a f o ld t h a t p ro tr u d e s
g r e a tly i n t o th e lum en.
o ccu rs i n th e m id d le
T his grow th o f c o n n e c tiv e t i s s u e which u s u a ll y
may o c c a s io n a lly be found n e a r e r th e pulm onary
end o f th e d u o tu s .
K ir s te in upon post-m ortem e x a m in a tio n o f a " n in e month f u ll te r m new­
born" found a f u n c tio n a l v a lv e p r e s e n t a t th e a o r t i c end o f th e duotus
and assumed t h a t a f u n c tio n a l v a lv e p ro b a b ly was p re s e n t i n a n o th e r
c ad a v e r f i f t y - o n e c e n tim e te rs i n le n g th .
He ag reed w ith Strassm ann r e ­
g a rd in g th e p re sen c e o f a v a lv e on th e b a s is o f t h i s e x trem ely sm all
number o f o b s e r v a tio n s .
T h is rid g e o f th e d u ctu s was n o t e s p e c i a l l y
la r g e and th e r e f o r e t h i s v a lv e o f th e d u ctu s was n o t la rg e enough t o
c lo s e th e e n tra n c e in to th e a o r t a .
He found t h a t th e d u ctu s c lo s e d f i r s t
in th e m iddle and th e c lo s u r e th e n p ro ceed ed tow ard b o th ends u n t i l th e
v a lv e a t th e a o r t i c end was re a c h e d .
w a ll a f t e r some w eeks.
T his v a lv e grew in to th e o v e rly in g
The in tim a c o n s is te d o f a th ic k meshwork o f v e ry
f in e e l a s t i c f i b e r s am ongst w hich m uscle c e l l s were i r r e g u l a r l y s c a t t e r e d .
E x te r n a lly th e in tim a was lim it e d by a n e l a s t i c a i n t e r n a .
The e l a s t i c
-7 2 -
and m u scu lar e lem en ts were a rra n g e d i n a v e ry d e f i n i t e o r d e r .
In d e n ta ­
tio n s o f th e r id g e s o r " p r o je c t io n s ” ( " P o l s te r " ) may be seen im m ediately
d i s t a l t o th e o r i g i n o f t h e l e f t pulm onary a r t e r y .
These " rid g e s " found
in th e in tim a o f th e d u o tu s a re on th e s id e i n c o n ta c t w ith th e w a ll o f
th e a o r ta w here th e la r g e e l l i p t i c a l a x is o f th e d u ctu s comes in c o n ta c t
w ith th e l e f t i n f e r i o r w a ll o f th e a o r t a .
These e l a s t i c and m uscular
m asses were seen o n ly i n th e p ro x im al p a r t o f th e ductus in th e f i f t y
o e n tim e te r newborn*
A t th e a o r t i c end o f th e ductus th e in tim a does
n o t c o n ta in such p r o je c tio n s or r i d g e s .
However, th e y a re s itu a te d
n e a r e r t o th e a o r t i c end o f th e d uotus th a n to th e pulm onary.
and m usoular elem en ts e x ten d e d however to th e a o r t i c e n tr a n c e .
The e l a s t i c
In th e
f o r t y - f o u r c e n tim e te r newborn d e f i n i t e e l a s t i c and m u scu lar m asses were
o b serv ed .
The " p o ls te r n " o r rid g e s w ere lo n g it u d in a lly a rra n g e d and were
o f uniform h e i g h t .
T h ick en in g o f th e in tim a d id n o t p ro g re s s w ith a g e .
When a marked e x te n s io n o f th e e l a s t i c and m u scu lar elem en ts was p r e s e n t,
th e lumen o f th e d u c tu s was l a r g e .
were sm all and low .
In th e narrow ed lumen th e s e elem en ts
The w a ll o f th e d u o tu s th e r e f o r e c o n ta in e d sm all
r id g e s s im ila r t o o th e r a r t e r i a l v e s s e ls c o n ta in in g a h ig h ly rid g e d in tim a .
The lumen i s i r r e g u l a r i n o u tlin e b ecau se o f t h i s v a r i a t i o n i n h e ig h t o f
th e in tim a .
Sclavounos ( '1 1 ) d e s c rib e s th e rid g e in th e d u ctu s a s ly in g betw een
th e lum ina o f th e two b ra n c h es o f th e pulm onary a r t e r y .
He s p e c u la te s
re g a rd in g i t s im portance i n o ases o f pulm onary embolism a s t o w h eth er
th e r e m ig h t be some c o n n e c tio n betw een th e developm ent and d isp la ce m e n t
o f t h i s rid g e to th e r i g h t o r to t h e l e f t , and th e p o s s i b i l i t y o f th e
l o c a l i z a t i o n o f a throm bus i n th e r i g h t o r l e f t lu n g .
Scalvounos c a l l s
-7 3 -
t h i s rid g e th e a r t e r i a l or pulmonary rid g e and d e s o rib e s i t s o r ig i n from
th e two l a t e r a l b ra n c h es o f th e m ain pulm onary tr u n k .
The
la te ra l
branches ( r i g h t and l e f t pulm onary a r t e r i e s ) a re m ost im p o rta n t a t f i r s t
and e n la rg e a t b i r t h when th e 'l u n g s b e g in t o f u n c tio n .
The
en larg em en t
o f t h e i r lum ina ta k e s p la c e a t th e expense o f th e p o s t e r i o r w a ll o f th e
pulmonary tr u n k .
As th e p o s te r io r edges o f th e two lum ina approaoh one
a n o th e r and u n i t e , th e y form a p e c u li a r septum w hich c o n s ti tu te s th e body
o f th e pulm onary r i d g e .
The s u p e r io r p a r t o f th e rid g e i s formed by a
fu s io n o f th e w a lls o f th e pulm onary a r t e r i e s a t r i g h t a n g le s w ith th e
r id g e .
A f te r b i r t h and w ith in c re a s e i n a g e , th e ductus g ra d u a lly becomes
o b l i t e r a t e d and th e r id g e o f th e d u ctu s d is a p p e a r s .
(See F ig . 17, page 4 1 ).
Linzenm eier d e sc rib e d a bending and ki n k in g o f th e d u c tu s oonoommitt a n t w ith a c o n tr a c tio n o f th e s p i r a l l y ru n n in g m u scu latu re w hioh le a d s to
th e fo rm a tio n o f r id g e s o r r i d g e - l i k e s t r u c t u r e s , ( " P o ls te r b ild u n g e n " ) .
A s th e r e s u lt o f a s h i f t i n p o s itio n o f th e th o r a c ic s t r u c t u r e s , th e ends o f
th e d u ctu s approach each o th e r .
The c o n tr a c tio n o f th e lo n g itu d in a l mus­
c u la tu re cau ses a k in k in g o f th e s id e o f th e duotus where i t i s s h o r t e s t .
Since a s l i g h t bending a lre a d y e x i s t s , th e low er w a ll o f th e ductus u n d er­
goes a g r e a te r c o n tr a c tio n and k in k in g .
(See F ig . 18, page 5 0 ).
He d id n o t f in d a v a lv e o f th e d u ctu s i n th e newborn a s p o s tu la te d
by Strassm ann b u t th e c a s ts o f th e lumen o f th e duotus o f th r e e newborns
dem onstrated th e p re se n c e o f a sm all e l l i p t i o a l rid g e on th e concave s id e
a t a sh arp a n g le to th e lum en.
From t h i s he deduced t h a t th e duotus
tu rn e d on i t s long a x is and b ro u g h t a b o u t a k in k in g .
lumina o f th r e e o th e r duotus were shaped l i k e
C asts made of th e
"hour-glasses" w ith
s t r i c t i o n s i n th e m id d le and t h i c k e r , e l l i p t i c a l e n d s.
con­
The lu e en w hich
-
74 -
was c o n s tr ic t e d where th e bending was m ost pronounced d id n o t e n t i r e l y
d is a p p e a r due t o th e m ech an ical s tr e n g th o f th e r o t a t i o n and bending*
G raper d is a g re e d w ith L inzenm eier a s t o th e bending and k in k in g o f
th e d u c tu s .
G raper f u r t h e r m a in ta in e d t h a t no v a lv e fo rm a tio n e x i s t s
e i t h e r a t th e a o r t i c o r pulm onary end of th e d u c tu s*
A s p u rio u s v a lv e - lik e arran g em en t can be p ro d u ced , how ever, by f i l l ­
ing th e d u ctu s w ith p l a s t e r under g r e a t p r e s s u r e .
S tra ssm a n n 's th e o ry
w hich i s based upon t h i s te c h n iq u e and th e r e s u l t i n g a r t e f a c t i s t h e r e ­
fo r e i n c o r r e c t .
The d ia m e te r o f th e lum ina o f th e two pulmonary a r t e r i e s
i s sm a ll; th e l e f t shows a deep rid g e pushed i n from behind so t h a t i t s
lumen does n o t ap p ear c i r c u l a r in c ro s s s e c t i o n .
A t th e a o r t i c e n tra n c e o f
th e d u c tu s, th e a o r ta and d u ctu s form a m utual w a ll and t h i s i s re g a rd ed
a s a v a lv e by S trassm ann.
In o n ly one o f s e v e r a l speoim ens d id G raper
f i n d th e e n tra n c e o f th e d u ctu s narrow and i r r e g u l a r l y s l it - s h a p e d and
surrounded by sm all knobby l i p s w hich he c o n sid e re d p a th o lo g ic a l.
The w a ll
o f th e d u ctu s was t h ic k e r th a n t h a t o f th e pulm onary a r t e r y and c o n ta in e d
i r r e g u l a r th ic k e n in g s form ed o f th e i n tim a .
These u n e q u a l, low e le v a tio n s
a re o fte n c lo s e ly p la c e d and s e p a ra te d by sm all g ro o v e s .
These e le v a tio n s
a re b e s t developed on th e up p er s u rfa c e o f th e lumen o f th e d u o tu s, l e s s
w e ll developed on th e low er s id e , an d ru n l o n g it u d i n a l ly i n a m a jo r ity o f
th e cases*
D ragendorf q u o tes th e work o f Fromberg a s su p p o rtin g th e v alv e form a­
t i o n a s m a in ta in e d by S trassm an n .
B e ttin g e r however m a in ta in s t h a t a sp u r
fo rm a tio n , p ro b a b ly a "v alv e o f Strassm ann" i s e s p e c i a ll y n o ti c e a b le .
The
in n e r s u rfa c e a c c o rd in g t o B e ttin g e r , a l s o c o n ta in s numerous lo n g itu d in a l
fo ld s *
-75
CONSIDERATIONS OF TIE VARIOUS DESCRIPTIONS AND EXPLANATIONS OF THE
RIDGE COR VALVEj
One o f th e f a c to r s u t i l i z e d in th e fo rm u la tio n o f th e o r ie s e x p la in ­
in g th e c lo s u re of th e d uctus is th e p re sen c e o f a v alv e o r v a lv e -lilc e
s tr u c tu r e *
Harvey s t a t e s t h a t " th e c a n a lis a r t e r i o s u s c o n ta in s no mem­
brane o r v alv e t o d i r e c t o r impede th e flow o f .th e blo o d in t h i s o r in
t h a t d ir e c tio n " - - - - "when th e h e a r t c o n t r a c t s , th e b lo o d i s r e g u la r ly
p ro p e lle d by th e c a n a l o r p assag e in d ic a te d from th e r i g h t v e n t r i c l e in to
th e a o r t a " .
S c h u ltz e 's o p in io n i s s im ila r to t h a t o f Harvey in t h a t he say s th e
ductus c o n ta in s no v a lv e .
Iiaberd a, S c h a rfe , L in zen m eier, K ir s te i n and
Schanz a ls o denied th e e x is te n c e o f a v a lv e o f th e d u ctu s a s d e s c rib e d by
S trassm an n .
Gundobin m a in ta in e d tlia t th e to r n "v alv e" was n o t a p p lic a b le
s in c e i t was v ery i r r e g u l a r l y developed and th e r e f o r e no v alv e a c t i o n was
in v o lv e d in th e c lo s u re of th e d u c tu s .
S trassm ann d e sc rib e d a v a lv e - lik e
fo rm a tio n o f th e a o r t i c w a ll over th e e n tra n c e o f th e d u ctu s in to th e a o r t a .
T his v a lv e - lik e fo rm a tio n i s th in n e r and more t r a n s l u c e n t th a n th e su rro u n d ­
in g a re a end i s s l i g h t l y concave in i t s f r e e e d g e.
The f i b e r s form a
" to n g u e -lik e " s tr u c tu r e e x te n d in g from th e d i s t a l end o f th e m e d ia l w a ll o f
th e ductus and can be seen m ic ro s c o p ic a lly t o p e n e tr a te a s a la y e r in to th e
a o rtic w a ll.
These v a lv e - lik e la m e lla o o f f i b e r s can be seen to e x ten d
f u r th e r in to th e ductus as a w h itis h -y e llo w l i n e e x te n d in g o n e -h a lf to
th r e e - q u a r te r s o f a c e n tim e te r in t o th e a o r t a , th u s c au sin g th e w a ll to
be s l i g h t l y e le v a te d .
T h is c o n d itio n , Strassm ann m a in ta in s , i s s im ila r
in th e sheep, dog, c a t and human f e t u s e s .
The l i n i n g o f th e d u ctu s a p ­
p e a rs s c a rre d and brow nish i n c o lo r ; th e c o v e rin g o f th e v a l v e - lik e
s tr u c tu r e i s somewhat sm oother and l i g h t e r in c o lo r th a n th e in tim a o f
-76 -
th e ductus*
He found th e v a lv e - lik e f o ld v e ry p o o rly developed i n a n
e ig h t m onth s t i l l b o r n .
However, he m a in ta in e d t h a t from th e f i f t h
month on, a s th e a n g le form ed by th e a o r t i c e n tra n c e of th e d u o tu s i n ­
c re a s e d , a d u p lic a tu r e o f th e a n t e r i o r w a ll o f th e ductus w ith th e a o r t i c
w a ll was form ed which covered over th e e n tra n o e o f th e d u ctu s in to th e
a o r t a i n a v a lv e - lik e m anner.
o f th e foram en ovale*
T h is v a lv e fo x m atio n was s im il a r t o t h a t
(See Fig* 12, page 35)*
S oharfe observed a s tr u o tu r e s im ila r t o th e one d e s c rib e d by S t r a s s ­
mann b u t d id n o t a g re e t h a t i t was definitely a v a lv e .
He m a in ta in e d t h a t
i t was an a r t e f a o t and n o t n e c e s s a ry because th e a o r t i c b lo o d d id n o t flo w
in to th e d u ctu s*
Kusohew on th e o th e r hand found S tra s s m a n n 's v a lv e
p r e s e n t in tw en ty p e rc e n t o f h is c a s e s .
Roeder su p p o rte d th e fin d in g s
o f Strassm ann and a ls o e la b o ra te d f u r t h e r a v a lv e - lik e f u n c tio n f o r th e
la m e lla e .
When p re s s u re i s in c re a s e d th e y a c t t o su p p o rt th e f l a p
(" v a lv e o f S trassm ann") a g a in s t th e p re s s u re e x e r te d by th e b lo o d p a s s ­
in g th ro u g h th e a o r t a , th u s p re v e n tin g a backflow in to th e d u c tu s and
pulm onary a r t e r y .
The re v e rs e flo w th ro u g h th e d u ctu s i s a l s o p re v e n te d
by th e n arrow ness of th e a c u te a n g le o f e n tra n c e o f th e d u ctu s in to th e
a o rta ,
H am ilton, Woodbury and Woods were a ls o a b le t o d em o n strate th e
e x is te n o e o f a v a lv e a t th e a o r t io e n tra n c e o f th e d u ctu s i n th e dog
and r a b b i t f e t u s .
In th e r a b b i t th e v a lv e c o n s is te d o f a p a i r o f f l a p s ;
in th e dog a s in g le f l a p formed th e v a lv e and th e r e f o r e th e b lo o d co u ld
o n ly flow from r i g h t t o l e f t or from th e d u ctu s in to th e a o r t a and n o t in
th e re v e rs e d i r e c t i o n .
-77
Fig. 8. Opening of mesenteric artery from ao rta in full term dog fetus.
Fig. 0. Opening of ductus arteriosus into ao rta in full term dog fetus. Note
valve-like membrane guarding opening,
j
Fig. 10. Longitudinal section through opening of ductus arteriosus in to ao rta in
full term rabbit fetus. One of the two valve-like flaps is shown.
^
\
F ig . 25. H am ilton, "Woodbury and Woods
HISTOLOGICAL COilSIDERATIOHS
The g ro ss m orphology o f th e d u o tu s lias been d e a lt w ith a t some
le n g th because o f th e many re s e a rc h e s c a r r ie d o u t in e f f o r t s t o d e t e r ­
mine changes o c c u rrin g in th e c i r c u l a t o r y system s h o r tly a f t e r b i r t h .
Even though th e h is to lo g y o f th e d u c tu s m s n o t s tu d ie d a s e x te n s iv e ly
a s i t s g ro ss m orphology, i t s h is to lo g y m s v a r io u s ly d o so rib e d by th e
d i f f e r e n t a u th o r s .
Same a u th o rs c o n sid e re d i t s s tr u c tu r e to be t h a t
o f a ty p i c a l a r t e r y w h ile o th e r s d e s c rib e d i t s h i s t o l o g i c a l s tr u c t u r e
a s b e in g p e c u lia r t o i t a lo n e .
K ilia n d e s c rib e d th e h i s t o l o g i c a l s tr u o tu r e o f th e d u ctu s as
s im ila r to t h a t of th e pulm onary a r t e r y whose c o n tin u a tio n i t fo rm s.
L anger, however, n o te d a g r e a t d iff e r e n c e in th e h is to lo g y of
th e pulm onary a r t e r y and th e a o r ta on th e one hand and th e d u ctu s in
th e s t i l l b o r n c h ild on th e o t h e r .
He o b serv ed t h a t th e w a ll o f th e
d u ctu s la ck e d a d e f i n i t e compact la y e r of e l a s t i c f i b e r s a s found in
o th e r la r g e a r t e r i e s .
Yfhite fib r o u s c o n n e c tiv e t i s s u e , how ever, was
more abundant in th e duotus th a n m s th e e l a s t i c c o n n e c tiv e t i s s u e
w hich in t h i s v e s s e l m s n o t w e ll d e v elo p e d .
The t h i c k e l a s t i c f i b e r s
o f th e media o f th e a o r ta d e c re a se i n amount tow ard th e ductus and
te rm in a te a t i t s m id d le .
T h is e l a s t i c bundle i s surrounded and p e n e tr a te d
-7 8 -
t y th e other ocnneatlve tissue elem ents o f th e d u o tu s .
The p e r ip h e r a l la y e r s
o f th e s e e l a s t i c f i b e r bundles c o n ta in more w h ite fib r o u s co n n ectiv e
t i s s u e th a n do th e d e e p e r, more i n t e r n a l l a y e r s .
(See F ig . 10, page 2 8 ).
H yaline and bloody m a t e r i a l a re p a r t l y i n f i l t r a t e d th ro u g h o u t th e s e
la y e r s and a t low m a g n ific a tio n s d ark b u n d le s o f e l a s t i c f i b e r s can a ls o
be s e e n .
F in e , lo o s e ly in terw o v en f i b e r s a rra n g e d in a manner s im il a r to
th e e l a s t i c f ib r o u s la y e r o f la r g e a r t e r i e s were found in th e a d v e n t i t i a
o f th e d u o tu s .
The s tr u c tu r e o f th e m edia w hich was s im ila r a ls o c o n ta in e d
t h ic k , tr a n s v e r s e a rran g em en ts o f c e l l s .
Among th e s e were is la n d s o f
lo n g itu d in a l c e l l - s t r a n d s w hich were more abundant among th e i n t e r n a l
la y e r s o f th e m edia and in c re a s e d i n number tow ard th e lumen of th e d u ctu s#
He was a ls o a b le t o i s o l a t e s h o r t sp in d le -sh a p e d c e l l s d is p e rse d th ro u g h o u t
th e c i r c u l a r la y e r s o f th e media w hich he b e lie v e d in c re a s e d th e th ic k n e s s
o f th e w a ll o f th e d u c tu s .
On t h i s b a s is he m a in ta in e d t h a t th e w a lls o f
th e duotus a r e s tr o n g e r th a n th e w a lls of th e pulmonary a r t e r y and th o s e
o f th e a o r t a .
W alkoff a ls o found t h a t th e media was n o t e n t i r e l y f r e e o f e l a s t i o
tis s u e .
In a f r e s h p r e p a r a tio n a d e lic a te e l a s t i c netw ork co u ld be found
c o n ta in in g c e l l e lem en ts and lo n g itu d in a l b u n d les w hich a re m ost abundant
a t th e a o r t i c e n tra n c e o f th e d u o tu s .
A m iddle c i r c u l a r la y e r o f m uscle
f i b e r s co u ld be d i f f e r e n t i a t e d from th e in n e r and o u te r lo n g itu d in a l l a y e r s .
These m uscle f i b e r s o f th e duotus were in terw o v en i n an e l a s t i c netw ork
t h a t i s f i n e r th a n t h a t o f th e pulm onary a r t e r y and a o r t a .
R a d ia lly a r ­
ranged m uscle f i b e r s were a ls o found among th e o u te r lo n g itu d in a l m uscle
la y e r .
The in tim a , however, d i f f e r e d from t h a t o f o th e r v e s s e ls in t h a t
th e e l a s t i c f i b e r s were lo o s e r and more w eakly dev elo p ed .
He a ls o o b -
-
79 -
serv ed sp in d le -sh a p e d elem en ts t o be p re s e n t w hich he b e lie v e d w ere de­
riv e d from an immature c o n n e c tiv e t i s s u e w hich l a t e r changes p a r t l y to
co n n ec tiv e t i s s u e and p a r t l y to e l a s t i c f i b e r s .
R a d ia lly and lo n g i­
tu d i n a l l y a rra n g e d c o lla g e n o u s t i s s u e of th e in tim a m s found a s a
s tro n g ly a d h e re n t la y e r betw een t h e rid g e s and f o ld s o f th e ductus*
He a ls o b e lie v e d t h a t th e \v a ll o f th e d u ctu s was s tro n g e r because o f
t h i s arrangem ent*
A ccording to Wrany th e lo n g itu d in a l la y e r s o f m uscle i n th e media
o f th e duotus were somewhat b e t t e r developed th a n th o s e o f th e a o r ta and
pulmonary a r t e r y .
These la y e r s a b r u p tly d e c re a se a t th e a o r t i c e n tra n c e
o f th e d u ctu s in th e newborn s in c e h y p e rtro p h y o f th o s e la y e r s had n o t y e t
se t in .
Thoma observed t h a t th e e l a s t i c and m u sc u la r la y e r s o f th e in tim a a re
b e s t developed in th e in n e r s u r f a c e o f th e d u o tu s i n th e re g io n o f th e
b i f u r c a tio n of th o pulm onary a r t e r y .
In t h e re g io n o f th e a o r t i c en­
tr a n c e , however, a u n ifo rm , r a t h e r th ic k e l a s t i c in te r n a i s p re s e n t w hich
s e p a ra te s th e in tim a from th e m e d ia .
The in tim a c o n ta in s a la rg e accumu­
l a t i o n o f m uscular e lem en ts ly in g among few e l a s t i c f i b e r s , t h a t u n i t w ith
th o se of th e media and form a t h i c k n etw o rk .
Because o f t h i s fu s io n th e
f ib e r s o f th e in tim a and m edia o f th e duotus a r e c o n tin u o u s w ith th e
in tim a and m edia of th e a o r t a , b u t th e s e t r a n s i t i o n a l m u scu lar and
e l a s t i c f i b e r s d i f f e r from th o s e in th e d u o tu s o r a o r t a .
The e l a s t i c
in te rn a however becomes i n d e f i n i t e and l o s t a t th e a o r t i c e n tra n c e o f th e
d u c tu s.
The m uscular p o r tio n i s a l s o d i f f i c u l t to f in d i n th e in tim a of
th e a o r ta below th e e n tra n c e o f th e duotus*
These m uscle f i b e r s o f th e
ductus a r e c o n tin u o u s w ith and su rro u n d th e e x b e rn a l s u r f a c e of th e a o r ta
-8 0 -
and c o n tin u e s u p e r io r ly and i n f e r i o r l y f o r s e v e r a l m illim e te r s o n ly .
D iffe re n c e s betw een th e m edia o f th e duotus and t h a t o f t h e a o r ta
and pulmonary a r t e r y were a l s o n o ted by Thama.
The m edia o f th e d uctus
la c k s a s tro n g e l a s t i c membrane b u t is p e n e tr a te d by d e lic a te membranes
and f i b e r s o f an e l a s t i c n a t u r e .
L o n g itu d in a l m uscle f i b e r s a r e m ixed
w ith e l a s t i o f i b e r s s im ila r i n n a tu re t o th o s e o f th e u m b ilic a l a r t e r y
b u t a r e g u la r c o n o e n tric arrangem en t o f th e s e la y e r s does n o t e x i s t so
t h a t th e m u scu lar and e l a s t i c p o rtio n s a re e q u a lly w e ll in te rm ix e d ,
Thama m a in ta in e d t h a t th e s e f i b e r s w ere caused t o p r o je c t i n t o th e lumen
o f th e duotus by means o f a c o n tr a c tio n o f th e m e d ia .
S in g le b ra n c h in g
c e l l s were found among th e s e la y e r s w hich Thama th o u g h t were c o n n e c tiv e
t i s s u e c e l l s because o f t h e i r s i m i l a r i t y t o th e i r r e g u l a r , b ran ch in g
m u scu lar c e l l s o f th e a o r t a .
A la r g e number o f o e l l s c o n ta in in g oval
and round n u o le i and d i f f e r i n g from th e s e c e l l s o f musjular c h a r a c te r a re
imbedded in a f in e f i b r i l l a r i n t e r c e l l u l a r su b sta n c e w hich Thama b e lie v e d s i ­
m ila r t o t h a t o f h y a lin e c o n n e c tiv e t i s s u e .
The n u c le i o f th e m uscle
f i b e r s a re a ls o s e p a ra te d from one a n o th e r by la r g e m asses o f t h i s homo­
genous, f i n e l y g ra n u la r i n t e r c e l l u l a r su b sta n c e ly in g w ith in th e e l a s t i o
la m e lla e whose f i b e r s a re s t i l l i n d e f i n i t e .
The m iddle and p a r t o f th e
in n e r zone o f th e media a p p ea rs lo o s e r and l i g h t e r .
Thama a tta c h e d
g r e a t im portance to th e s e changes w hich he b e lie v e d were th e r e s u l t of
a d e g e n e ra tiv e p ro c e ss r e s u l t i n g in a h y a lin e change in th e media o f th e
d u o tu s.
Schanz, c o n tr a r y t o th e f in d in g s o f Thoma, m a in ta in e d t h a t th e c i r ­
c u la r m uscle i s n o t s tro n g enough to c o n tr a c t th e d u c tu s and cau se i t s
c lo s u r e .
L o n g itu d in a l s e c tio n s o f th e duotus i n two newborns showed th e
m uscle c e l l s o f th e c i r c u l a r la y e r ly in g a g a in s t one a n o th e r b u t s e p a ra te d
-8 1 -
from s im ila r o th e r la y e r s by a r e g u l a r netw ork t h a t i s c h a r a c t e r i s t i c
o f smooth m u s c le .
The e l a s t i c and f i b r i l l a r c o n n e c tiv e t i s s u e c e l l s
a r e a rra n g e d p a r a l l e l t o th e long a x is o f th e d u c tu s .
B a rt o f th e media
was s e p a ra te d i n t o two la y e r s by a n arro w spaoe w h ich m s p a r t i a l l y
f i l l e d w ith c o n n e c tin g bun d les u n itin g th e s e la y e r s o f c i r o u l a r m uscle#
The a d v e n t i t i a l i e s e x te r n a l t o t h i s la y e r and i s o f an e l a s t i c c h a r a c te r ;
i t s o u te r s u rfa c e c o n ta in in g a la y e r o f lo o se c o n n e c tiv e t i s s u e .
S c h a r f e 's te c h n iq u e i n s tu d y in g th e d u ctu s h i s t o l o g i c a l l y c o n s is te d in
stu d y in g sm a ll s e c tio n s from th e pulm onary a r t e r y , a o r t a , d u o tu s and ju n c tio n
o f th e d u ctu s and a o r t a .
The in tim a o f th e d u ctu s was r i c h l y i n f i l t r a t e d w ith
m usole c e l l s ly in g a m o n g s t'its v e ry lo o se c o n n e c tiv e t i s s u e .
F ig . 2 6 .
Scharfe
E la s tic fib e rs
-8 2 -
were e n t i r e l y la c k in g .
An e l a s t i c membrane betw een th e in tim a and
m edia was found o n ly a t th e a o r t i c opening o f th e d u c tu s .
T his membrane
was h a rd ly d is o e r n ib le i n th e m iddle o f t h e d u ctu s w hich he s t a t e s form s
th e s i t e o f e a r l i e s t c lo s u r e .
The in tim a w hich was a rra n g e d in fo ld s
co u ld be e n t i r e l y removed from i t s base by means o f a lc o h o l f i x a t i o n .
He a ls o b e lie v e d t h a t th e r e g u la r arran g em en t o f th e c o n c e n tric la y e r s
le a d s to a s tro n g m u scu lar c o n t r a c ti o n . ( F ig . 2 6 ).
Kuschew employing th e W eig ert te c h n iq u e s ta in e d th e duotus o f a
f iv e month o ld f e tu s and was a b le t o d i s ti n g u is h th r e e l a y e r s ; th e
in tim a , m edia and a d v e n t i t i a .
An e l a s t i c a in te r n a formed a boundary membrane
betw een th e in tim a and m edia, b u t no membrane e x is t e d betw een th e media and
a d v e n titia .
The in tim a c o n s is te d o f s tro n g , f in e fib e re d t i s s u e w ith few,
s p in d le -sh a p e d ro u n d -c e lle d e le m e n ts .
a rra n g e d i n c o n c e n tric l a y e r s .
Between th e c o n c e n tric la y e r s were found
some lo n g itu d in a l m uscle b u n d le s .
c irc u la r e la s tic f ib e r s .
The m edia c o n ta in e d m u s c l e 'c e lls
The a d v e n t i t i a c o n ta in e d m ost o f th e
The w a ll o f th e d u c tu s , a c c o rd in g t o Kuschew,
becomes s tr o n g e r th a n t h a t of th e a o r t a and pulmonary a r t e r y in th e seven
month o ld f e t u s due t o a th ic k e n in g of th e w a ll o f th e ductus w hich r e s u l t s
from a c o n n e c tiv e t i s s u e grow th .
G erard a ls o b e lie v e d th e sp in d le -sh a p e d c e l l s to be smooth m uscle
c e lls .
These were found a s numerous la y e r s i n th e meshes o f th e netw orks
o f e l a s t i c and c o lla g e n o u s c o n n e c tiv e t i s s u e e x te r n a l t o th e e l a s t i c a
in te rn a .
P f e i f f e r on th e o th e r hand a s a r e s u l t o f h is re s e a rc h e s concluded
t h a t th e r e i s no d if f e r e n c e i n m o rp h o lo g ic a l s t r u c t u r e betw een th e duotus
and o th e r la r g e a r t e r i e s suoh a s th e a o r t a .
The en d o th eliu m i s t h i n and
-8 3 -
and i n f i l t r a t e d w ith s h o r t rounded o e l l s ly in g w ith in la y e r s o f oonn e o tiv e t i s s u e t h a t g r a d u a lly merge i n t o th e e l a s t i c t i s s u e o f th e m ed ia.
The media c o n s is ts of t h io k bands o f c i r c u l a r e l a s t i o f i b e r s a l t e r n a t i n g
w ith la y e r s o f c i r o u l a r bands o f smooth m uscle t h a t a re p e n e tr a te d by
e la s tic fib e rs .
These f i b e r s b r in g a b o u t a v e ry in tim a te u n io n o f a l l
th e e l a s t i c elem en ts o f th e tu n ic a m e d ia .
The d u c tu s i s r io h in e l a s t i c
t i s s u e which does n o t d i f f e r i n arran g em en t from t h a t o f any o th e r a r t e r y
o f s im ila r s i z e .
The a d v e n t i t i a o f th e d u ctu s c o n ta in s v ery f in e e l a s t i c
f i b e r s which form a v e ry d e l i c a t e n etw o rk in whose meshes c o n n e c tiv e
t i s s u e , m u scu lar elem ents and v e s s e ls a re fo u n d .
P f e if e r a ls o m a in ta in e d
t h a t th e s p in d le -sh a p e d c e l l s were i d e n t i c a l w ith smooth m u sc le .
Ilis
d e s c r ip tio n o f th e a d v e n t i t i a i s s im ila r to t h a t o f Kuschew and G erard .
Argaud p re p a re d tr a n s v e r s e s e c tio n s o f th e d u ctu s of a human f iv e
month old f e tu s and s tu d ie d th r e e re g io n s o f i t , nam ely, a t b o th ends
and i n th e m id d le .
In th e m iddle r e g io n , th e d u c tu s changes to a mus­
c u la r ty p e , th e in tim a b e in g reduced to a s in g le la y e r o f en d o th eliu m
t h a t i s v ery much c o rru g a te d i n t e r n a l l y .
His d e s c r ip ti o n o f th e media
d i f f e r s from t h a t o f o th e r i n v e s t i g a t o r s .
i s formed e x c lu s iv e ly o f c i r c u l a r
fib e rs .
The m edia a cc o rd in g t o Argaud,
m uscular f i b e r s and v e ry s h o rt c l a s t i c
The s e c tio n a t th e a o r t i c e x tre m ity o f th e d uctus c u t th e a o r ta
tr a n s v e r s e ly and th e d uctus l o n g i t u d i n a l l y .
The w a ll o f th e a o r ta con­
ta in e d many la y e r s o f com pressed e l a s t i c t i s s u e .
These la y e r s o f e l a s t i c
t i s s u e te rm in a te around th e a o r t i c o r i f i c e o f th e d u o tu s .
The lim it in g
in te rn a however c o n tin u e s from one v e s s e l in to th e o th e r .
The c o v e rin g
o f th e pulm onary a r t e r y undergoes an e q u a lly a b ru p t t r a n s i t i o n , th e
e l a s t i c la y e r s g ra d u a lly d im in ish i n number and th ic k n e s s s in k in g i n t o
th e w a lls o f th e " c o n ic a l c u l- d e - s a c " w hich g iv e s r i s e t o th e a re a o f
-8 4 -
im p la n ta tio n o f th e d u o tu s .
The endothelium aeo o rd in g to K lo tz ( ’07) r e s t s on a la y e r o f con­
n e c tiv e t i s s u e t h a t i s f a i r l y lo o s e and a p p e a rs q u ite p rom inent when
th e duotus i s c o lla p s e d .
T h is in v e s t i g a t o r found th e c o n n e c tiv e t i s s u e
la y e r s tr e t c h e d o u t and t h i n in th e d i l a t e d d u c tu s , how ever, b e n e a th t h i s
la y e r l i e s a much in te r r u p te d i n t e r n a l e l a s t i c membrane t h a t i s made up
o f i r r e g u l a r s tra n d s t h a t o v e rla p e ac h o th e r when c o n tr a c te d .
T his i n ­
t e r n a l e l a s t i c membrane does n o t form a conspicuous elem ent i n th e form ­
a t i o n o f th e duotus a s i n o th e r m u scu lar v e s s e ls b u t r a t h e r c o n s is ts of
s e v e r a l t h i n lam inae r a t h e r th a n one heavy on e.
The m ed ia, deep to t h i s
l a y e r , c o n s is ts alm o st e n t i r e l y o f m u sc u la r t i s s u e w ith a f in e netw ork o f
e l a s t i c f i b e r s t h a t in te r tw in e and b in d th e m uscle b u n d les t o g e th e r .
The
c i r c u l a r m uscle bun d les exceed i n number th e lo n g itu d in a l m uscle b u n d les
w hich have no fix e d p o s itio n in th e m ed ia.
The c i r c u l a r f i b e r s o f th e
media a re n o t r e g u la r ly a rra n g e d as in o th e r a r t e r i e s , how ever, th e a d ­
v e n t i t i a i s s im ila r t o t h a t o f o th e r v e s s e l s .
l i i r s t e i n a ls o d e sc rib e d d e f i n i t e e l a s t i c and m u scu lar a r e a s in th e
re g io n o f th e a o r t i c e n tra n c e o f th e duotus i n th e f o r t y - f o u r o e n tim e te r
fe tu s .
A marked e x te n s io n o f th e s e e l a s t i c and m usoular elem en ts e x is t e d
when th e lumen o f th e ductus vras l a r g e .
He a ls o observed lo n g itu d in a l
rid g e s o f d e f i n i t e h e ig h t which in th e c o n tra c te d lumen a re sm all and low .
F aber does n o t a g re e w ith P f e i f e r re g a rd in g th e h is to lo g y o f th e
d u o tu s.
F aber found an in te r n a l e l a s t i c membrane t h a t i s alw ays d o u b le ,
v a r ie s somewhat i n th io k n e s s and i s s t r i a t e d l o n g i tu d i n a l ly b e n e a th th e
endothelium and very t h i n c o n n e c tiv e t i s s u e .
E x te rn a l t o t h i s membrane
i s found a la y e r o f c i r c u l a r , lo n g itu d in a l and o b liq u e ly ru n n in g e l a s t i c
85-
and m usole f i b e r s t h a t i s g ra d u a lly co n tin u o u s w ith th e more e x te r n a l
i r r e g u l a r m uscle b u n d les of th e m ed ia.
The d i s t r i b u t i o n o f lo n g itu d in a l,
o b liq u e and c i r c u l a r f i b e r s change a s th e p e r ip h e r y o f th e w a ll of th e
d u ctu s i s ap p ro ach ed , th e c i r c u l a r f i b e r s become more p red o m in an t.
The
e l a s t i c t i s s u e o f th e media i s r a t h e r s tro n g and e x ten d s t o th e m usoular
p a rt.
The a d v e n ti tia i s v e ry r ic h i n e l a s t i c f i b e r s , th e in n e r la y e rs
c o n ta in more c i r c u l a r and o b liq u e f i b e r s ; th e o u te r la y e r s more lo n g i­
tu d in a l f ib e r s .
Ho e l a s t i c a e x te r m was o b serv ed .
L in z e n m e ie r's d e s c r ip ti o n o f th e h is to lo g y o f th e d u c tu s i s s im ila r
to t h a t o f F a b e r.
S c h a f f e r , quoted by m elka, a ls o found t h a t s p l i t t i n g o f th e e l a s t i c
la m e lla from th e e l a s t i c in tim a o c c u rre d in th e newborn p i g .
G raper vras a b le to show by s ta i n in g w ith R e s o rc in -fu c h s in , and a l s o
W eig ert s t a i n , t h a t th e ductus d if f e r e d in h i s t o l o g i c a l s tr u o tu r e from
t h a t o f o th e r a r t e r i e s .
Where th e in tim a i s t h i n , th e e l a s t i c a in te r n a
can be seen t o be formod by th e u n io n o f s e v e ra l la m e lla e *
The m ost e x ­
t e r n a l l y lo c a te d o f th e s e la m e lla e form s th e b o rd e r betw een th e in tim a
and th e m edia and a p p ea r co n tin u o u s a s a s tr o n g e r , f r e q u e n tly broken w ind­
in g l i n e ly in g u n d er th e i n t e r n a l th ic k e n in g s .
in g s a re o th e r t h i n la m e lla e .
I n te r n a l to th e s e th io k e n -
These la m e llae p e n e tr a te th ro u g h th e se
th ic k e n in g s and beoome th i n n e r , th e more num erous, broken up and t h ic k e r
th e rid g e s a r e .
These th ic k e n in g s or rid g e s c o n ta in c o lla g e n o u s and
e l a s t i c c o n n e c tiv e t i s s u e .
E x te rn a l to t h i s la y e r th e r e a re numerous
s p in d le and s ta r -s h a p e d anastom osing c e l l s t h a t G raper b e lie v e s a re
s im ila r t o th e c e l l s o f Langhans and a re u n d o u b ted ly m uscle o e l l s .
The
m edia i s u n ifo rm ly th io lc b u t does n o t c o n ta in an e l a s t i c a e x te rn a d e lim itin g
-8 6 -
i t from th e a d v e n t i t i a .
a rte rie s .
The m edia i s more open and i r r e g u l a r th a n i n
I t i s m ost r e g u la r however when th e r id g e s o r in tim a a re
p o o rly d e v elo p e d .
He was a b le t o d i s tin g u is h i n t h i s case a r e g u la r
lo o se lo n g itu d in a l m uscle la y e r w hich had e x te r n a l to i t a t h i c k , lo o s e ly
a rra n g e d c i r c u l a r l a y e r .
Betvreen th o s e two la y e r s f l a t b u n d les o f lo n g i­
tu d in a l m uscle f i b e r s a re a ls o fo u n d .
I f rid g e s a re p re s e n t th e in n e r
lo n g itu d in a l m uscle la y e r i s ir r e g u la r and i n some p la c e s may be c o m p le te ly
la c k in g .
Under th e s e r id g e s a re found th ic k e n in g s t h a t form s tro n g
b u n d le s up t o o n e - h a lf m illim e te r th ic k c o n ta in in g f i b e r s ru n n in g in a
s p ir a l d ire c tio n .
Spaces up to o n e - th ir d m illim e te r in s iz e l i e in a
r e g u la r m anner i n th e o u te r m uscle la y e r c lo se to th e s e b u n d le s .
There
i s no d e f i n i t e w a ll to th e s e s p a c e s, b u t G raper s t a t e s t h a t th e y a re n o t
a rte fa c ts .
His fin d in g t h a t e l a s t i c f i b e r s a re p r e s e n t in th e media i s
c o n tr a r y to th e f in d in g s o f o th e r i n v e s t i g a t o r s .
The a d v e n t i t i a i s n o t
v e ry d i f f e r e n t from t h a t o f o th e r a r t e r i e s e x c e p t t h a t th e v asa vasorum
a r e v e ry num erous,
P o ll o t (*09) s tu d ie d a s i x month and a ls o a f o r t y week f e t u s and
d e so rib e d a d e lio a te netw ork o f e l a s t i c t i s s u e i n th e m edia, th e o u te r
p o r tio n c o n ta in in g m a in ly c i r o u l a r l y a rra n g e d smooth m usole.
The in tim a
and m edia a re s e p a ra to d from one a n o th e r by an e l a s t i o a i n t e r n a .
The
e l a s t i o f i b e r s o f th e m edia a re m o stly e i r o u l a r i n th e f o r t y week f e t u s .
The e l a s t i c a in tim a i s e le v a te d on th e in n e r s u rfa c e o f th e w a ll o f th e
d u c tu s .
He does n o t c o n s id e r t h i s to be norm al in a duotus t h a t i s n o t
y e t o b l i t e r a t e d f o r suoh an e le v a tio n i s n o t found i n th e s ix m onth o ld
fe tu s .
He m a in ta in s t h a t i t a p p ea rs a s th e e x p re s s io n o f a p rem atu re
o b l i t e r a t i o n , w hich i s norm al i n th e newborn t h a t h as a lr e a d y b r e a th e d .
-8 7 -
Mellca s tu d ie d th e h is to lo g y o f th e d uotus i n e le v e n f e tu s e s from
5 .5 o e n tim e te rs to a c h i l d t e n m onths o l d .
The o r o s s - s e c tio n o f th e
duotus o f th e 5 .5 c e n tim e te rs c ra w n -h ee l le n g th f e tu s showed th e in tim a
t o c o n s is t o f squamous e p ith e liu m and a n o tic e a b le e l a s t i o a in tim a w hich
forms a u n ifo rm , wavy la m e lla t h a t i s o c c a s io n a lly p re s e n t a t th e p u l­
monary e n d .
T h is la m e lla i s n o tic e d a t th e f i r s t o n s e t o f t h a t grow th
w hich l a t e r c a u se s o b l i t e r a t i o n .
The m edia o o n ta in s e l a s t i c f i b e r s ,
a rra n g e d m a in ly c i r c u l a r l y and u n ite d by a v e ry f in e r a d i a l n e t o f
e la s tio f ib e r s .
Some o f th e s e f i b e r s ru n l o n g i tu d in a lly .
On u s in g
H em atoxylin and Van G ieson s t a i n th e m edia was seen to c o n ta in s p in d le shaped elem ents w ith long re d -s h a p e d n u c le i and y e llo w c o lo re d p lasm a.
Melka a g re e s w ith o th e r s in r e f e r r i n g t o th e s e sp in d le -sh a p e d c e l l s a s
smooth m u so le .
These lo n g itu d in a l b u n d les a re a rra n g e d a s in n e r and
o u te r la y e r s o f th e m edia and betw een th e s e two th e s tro n g e r m iddle
c i r c u l a r la y e r i s fo u n d .
The s tr u o tu r e o f th e m edia i s r a t h e r lo o s e due
t o th e weak u n io n o f th e s e l a y e r s .
The a d v e n t i t i a i s embryonic i n o h a r-
a o te r and f i l l e d w ith numerous embryonic c o n n e c tiv e t i s s u e o e l l s c o n ta in ­
in g a few t h i n c o lla g e n f i b r i l s .
The d u ctu s in th e e ig h t and f i f t e e n
c e n tim e te r f e tu s i s a l s o s im ila r e x o ep t t h a t bundles o f smooth m usole
f i b e r s a r e found in th e meshes o f th e e l a s t i c f i b e r n e tw o rk s.
The
p e r ip h e r a l p a r t o f th e m edia c o n ta in s same c o lla g en o u s c o n n e c tiv e t i s s u e
t h a t a r i s e s p a r t l y i n - s i t u and p a r t l y from th e a d v e n t i t i a .
In th e tw e n ty -
one o e n tim e te r f e tu s th e c o lla g e n o u s c o n n e c tiv e t i s s u e p r o l i f e r a t e s t o
f o r a h a l f th e th ic k n e s s of th e m ed ia; th e e l a s t i c f i b e r s o f th e m edia b e ­
coming t h i c k e r e x t e r n a l l y .
The lumen o f th e duotus o f th e 25 cm. f e t u s in lo n g itu d in a l s e c ti o n
i s o o n s tr ic te d by r id g e s t h a t a r i s e a s a r e s u l t o f an i r r e g u l a r grow th
-8 8 -
o f th e e l a s t i c in tim a .
T h is e l a s t i o a in tim a o f th e d u ctu s i s co n tin u o u s
w ith th e e l a s t i o a in tim a o f th e a o r t a and pulm onary a r t e r y .
The tu n ic a
media i s formed o f b u n d le s o f smooth m usole, a rra n g e d m a in ly in th re e
la y e r s ; a n o u te r and in n e r lo n g itu d in a l and a m iddle o i r o u l a r l a y e r .
The
musole c e l l s a re imbedded in a n e t o f e l a s t i c f i b e r s w hich i s th in n e r and
f i n e r in th e duotus th a n i n th e a o r t a and pulm onary a r t e r y .
The f i b e r s
a re a rra n g e d p r im a r ily i n a o i r c u l a r manner w ith seme lo n g itu d in a l f i b e r s
u n ite d in to a netw ork th ro u g h f i n e , r a d i a l l y a rra n g e d f i b e r s .
However, th e
s tro n g e l a s t i o la m e lla e o f th e a o r t a and pulm onary a r t e r y do n o t c o n tin u e
in to th e w a ll o f th e d u o tu s .
The c o lla g e n o u s c o n n e c tiv e t i s s u e o f th e
media f i r s t a p p ea rs i n th e e x te r n a l la y e r s o f th e media and in o re a s e s in
th ic k n e s s w ith developm ent a r i s i n g p a r t l y from th e a d v e n t i t i a and p a r t l y
i n - s i t u i n th e m edia i t s e l f .
T ran sv e rse s e c tio n s o f th e d uotus in th e s t i l l b o r n e x h i b i t s tro n g
r id g e s t h a t p r o je c t i n t o th e lumen and a r e oovered w ith low en d o th eliu m .
These rid g e s c o n s is t o f s tro n g e l a s t i c f i b e r s t h a t a r i s e th ro u g h grow th
o f th e e l a s t i o in tim a w hich i n seme re g io n s o f th e d uotus i s formed by
th e u n io n o f s tro n g la m e lla e .
p o rtio n o f th e d u o tu s .
These r id g e s a r e g r e a t e s t in th e m id d le
I n tr a n s v e r s e s e c tio n o f th e tw en ty -o n e day o ld
in f a n t la r g e r id g e s p r o j e c t in to t h e lum en.
These lo n g itu d in a l r id g e s ,
Iilelka b e lie v e d , a re form ed from e l a s t i o in tim a and o o n s is t o f e l a s t i o
f i b e r s t h a t a r i s e from th e p r im itiv e e l a s t i o in tim a , o o lla g e n o u s f i b e r s
and musole c e l l s .
I r r e g u l a r l y d is p e r s e d a r e a s o f smooth m uscle a re a ls o
found among r a d i a l l y a rra n g e d sp aces t h a t a re i n f i l t r a t e d w ith o o lla g e n o u s
c o n n e c tiv e t i s s u e .
M uscle o e l l s a re more numerous th a n o o lla g e n o u s and
e l a s t i o t i s s u e i n th e m ed ia, how ever, th e e l a s t i c t i s s u e i s e s p e c i a l l l w e ll
d eveloped, in th e e x te r n a l la y e r s o f th e m e d ia .
The a d v e n t i t i a o o n s is ts
-
89 -
m a in ly o f o o lla g e n o u s c o n n e c tiv e t i s s u e *
D ragendorf surveyed e x te n s iv e ly th e l i t e r a t u r e on th e h is to lo g y of
th e d u otus b u t does n o t r e f e r t o any work he may h im s e lf have c a r r i e d
out*
C osta employed s e v e r a l s ta i n in g te c h n iq u e s t o i d e n t i f y th e v a rio u s
c o n s ti tu e n ts of th e w a ll o f th e d u o tu s .
He i d e n t i f i e s th e in tim a a s t h a t
p o r tio n o f th e w a ll t h a t l i e s betw een th e e n d o th eliu m and th e i n t e r n a l
e l a s t i o lim it in g membrane.
s iz e d .
Four p e c u l i a r i t i e s o f th e in tim a a re empha­
( l ) The upper th ic k e n in g and i r r e g u l a r h e ig h t* (2) A s o a r o ity of
e l a s t i c t i s s u e . ( F ig . 27, 2 8 ) . (3 ) The rio h n e s s o f lo n g itu d in a l m u scu lar
o e l l s . (4 ) The in te n s e a b so rb in g o f muous s u b s ta n c e .
The in tim a was
t h i c k e r th a n i n th e a o r ta "Up to th e b e g in n in g of f e t a l l i f e " .
because o f i t s s iz e th e r e f o r e enoroaohed upon th e m e d ia .
The i r r e g u l a r i t y
Fw . 2. •
S r i i u n r . a j i i t a l r in <o f f i - |iu ti tlf tiia d r l l o .|ti»
.I tn rrri« d r l d n llii n r l l 'a o r t a .
( d e l e r u i e t h * J r l l r f iiir r r l u - l i i l i r ; I m iii Ium o >li du«*
u<- it
mi co ol .. I».
( l . M T u r r la |i r u |i i f |t i i i r rlie
1« |tarH* d r l d n ttu i n t i a ruiuMmrnif
i- r a m a lm r n li- ' m l l o t j i r t t o r r d r l l a |iarr te a o r t i r * . ( S o la rr m u In la |n **I if »-i ^
tiitniah- (|«-1 d o lln «• la i|» rr(ila* ia d r l l #
MM r l M i r i i n i r r n a .
K it.. I .
N * iiu n r in t o r n
f |M -r|it-m iir« iU rr a l l '.
<K o l o r d im n r ili ll>- l i l x r < I j - I i i Ihh. .
<11 H h f r <’id -lirh < ' r <|win<li I 'j l l l . t j . (•
• o ltu I Y m l» lr llo < .
F ig . 2 7 .
Tho in tim a
C osta
F ig . 28.
C osta
in th ic k n e s s o f th e in tim a oaused th e lumen to a p p e a r u n d u l a t i n g .
The
i n t e r n a l e l a s t i o membrane i s t h i n , s i n g l e , c le a n and w e ll c o lo re d ; i n
-9 0 -
th e e a r l y s ta g e s i t i s t h i n and p a le when s ta i n e d w ith M allo ry s ta in *
I t s t a i n s p r o g r e s s iv e ly d a rk e r w ith in c r e a s e in f e t a l age*
a r e th in n e r a t th e e ig h th month*
The f i b e r s
The t h i o k in tim a o o n ta in s lo n g i­
t u d i n a l m usole la y e r s t h a t a re i n t e r n a l t o th e i n t e r n a l e l a s t i o membrane*
T h is m u scu lar la y e r o f th e in tim a forms a t th e b eg in n in g o f f e t a l l i f e
and in o re a s e s w ith a g e , a p p e a rin g d u rin g th e f i r s t few months o f f e t a l
l i f e a s a n e a r ly compact la y e r o f m uscle c e l l s t h a t re a c h e s i t s f u l l de­
velopm ent a t th e end o f i n t r a - u t e r i n e l i f e *
The m edia was found t o be s im ila r t o t h a t o f o th e r la r g e b lo o d
v e s s e ls w ith th e e x c e p tio n t h a t mucoid su b sta n c e was a b so rb e d , e s p e c i a l l y
in th e i n t e r n a l tw o -th ird s o f th e media*
I 'n
Fig* 29*
Costa
-9 1 -
C osta a l s o d i f f e r e n t i a t e s i n th e i n t e r n a l tw o - th ir d s o f th e m ed ia,
a la y e r o f c i r c u l a r m usole, and e x te r n a l t o t h i s an o b liq u e and l o n g i ­
t u d in a l l a y e r .
spongy.
The i n t e r n a l tw o - th ir d s o f th e media a p p e a rs p u ffe d and
A mucoid su b sta n o e form s la rg e drops i n th e in tim a and m edia
and i s c h a r a c t e r i s t i c o f th e d u o tu s .
( F ig . 29, No* l ) .
P re c o lla g e n o u s
and c o lla g e n o u s t i s s u e i s s c a ro e d u rin g e a r l y f e t a l l i f e and in o re a s e s
w ith a g e , becoming d is p e rs e d betw een th e m usole c e l l s and th e f i r s t p a r t
o f th e a d v e n t i t i a .
C osta em phasizes th e p re se n c e o f lo n g itu d in a l m uscle in th e in tim a
w h ile o th e r in v e s t i g a t o r s had d e so rib e d th e lo n g itu d in a l m usole a s b e in g
i n th e m edia*
Ilayek a ls o d e s c rib e d th e d uotus a s d i f f e r i n g from o th e r la r g e v e s s e ls
i n t h a t i t la c k s a n e l a s t i o la m e lla , b u t c o n ta in s a membrana e l a s t i o a in te rn a .
The m u so u la tu re i s s e p a ra te d by a c i r c u l a r la y e r i n t o a n in n e r
and o u te r lo n g itu d in a l l a y e r .
The f i b e r s o f th e o i r o u l a r la y e r ru n ob­
liq u e ly i n a s p i r a l arrangem ent t h a t i s s im i la r to th o s e i n th e u m b ilic a l
a rte rie s .
T ra n sv e rse and lo n g itu d in a l s e c tio n s th ro u g h th e narrow ed p a r t
o f th e d u o tu s show a d e f i n i t e o u te r la y e r in w hich th e f i b e r s ap p ro ach a
lo n g itu d in a l a rra n g e m e n t.
However, a l l th e s e f i b e r s a p p e a r c i r c u l a r i n a
o ro s s s e c tio n o f th e d u ctu s when i t has been s t r e to h e d .
The f i b e r s ru n
i n o b liq u e s p i r a l l i n e s ; t h a t a re l e s s slo p ed th a n a r e th o s e ly in g o lo s e r
t o th e lumen o f th e d u o tu s .
These f i b e r s w hich a re a rra n g e d i n f l a t
b un d les o r la y e r s s im ila r t o th e u m b ilio a l a r t e r y a l s o c ro s s eaoh o th e r
a t v a rio u s a n g le s .
Hayek says i n re fe re n c e to th e r id g e s t h a t " I t seems
p ro b a b le t o me t h a t such musole r id g e s a re preform ed i n o n ly a few p la c e s
and th e m usole f i b e r s p r o je o t in betw een th e more s p l i t la m e lla e o f th e
-
e la s tio a in te r n a .”
92 -
(F ig , 3 0 ).
Abb. 16. L&ngsschnitt durch den Abgang des
jDuetus Botalli aus der Aorta. Neugeb.,
■30 cm gr. Lg. Orcein. lOf. D .B . Duotus
,
Botalll, A o. Aorta, P . Pulmonalls.
H.g. 3 0 ,
Hayek
As can r e a d i l y be seen a wide d iv e rg e n ce o f o p in io n e x i s t s a s t o
th e h is to lo g y o f t h e d u o tu s .
T h is h a s le d t o many i n t e r p r e t a t i o n s o f
th e f u n c tio n o f th e v a rio u s components o f th e duotus*
INTERNAL BLEEDING
S e v e ra l i n v e s t ig a to r s have d e so rib e d a c o n d itio n o f i n t e r n a l t e a r ­
in g and b le e d in g o c o u rrin g i n th e w a ll o f th e d u c tu s .
Roeder m a in ta in e d
t h a t th e p o s s i b i l i t y o f te a r in g th e w a ll o f th e duotus i n th e newborn
was v e ry g r e a t due t o a o a n b in a tio n o f i t s i r r e g u l a r o o n tra o tio n and th e
cram ping fo r c e e x e r te d by th e f i r s t b r e a th .
H y alin e changes showing d e­
g e n e r a tio n w ere observed by o th e r i n v e s t ig a to r s suoh a s Thama, Haberda
-9 3 -
and P o l l o t .
The lumen c o n ta in e d i n f i l t r a t e d plasm a and c e l l u l a r e lem en ts
which G raper found w ith g r e a t r e g u l a r i t y n e a r th e lo n g itu d in a l m uscle
bundles o f th e in n e r lo n g itu d in a l l a y e r .
He a ls o ob serv ed hemorrhage
r e g u la r ly o c c u rrin g i n th e newborn and in o ld e r c h ild r e n .
ROTATION. SHIFTING AND TOPOGRAPHIC CHANGES
W alkoff b e lie v e d t h i s b le e d in g and te a r in g to be caused by a s h i f t i n
p o s itio n of th e d u ctu s whioh i n tu r n le a d s t o i t s c lo s u r e .
Lowering of
th e diaphragm and th e h e a r t r e s u l t s i n a more pronounced a rc h in g o f th e
a o r ta and change i n p o s itio n and a n in c re a s e d bending o f th e d u o tu s .
As
b re a th in g c o n tin u e s th e hilu m of th e lung moves forw ard and oauses a
t r a o t i o n on th e b i f u r c a t i o n o f th e pulmonary a r t e r y so t h a t a v a lv e - lik e
c lo s u re o f th e duotus o c c u r s .
S c h u ltz e o n th e o th e r hand d id n o t fa v o r
t h i s forw ard t r a c t i o n , b u t b e lie v e d t h a t th e c lo s u re m s due t o a lo w erin g
o f th e diaphragm w hich p u lls down th e h e a r t and hilum o f th e lu n g , th u s
m odifying th e d i r e c t i o n o f th e d u c tu s and c a u sin g i t to become f o ld e d .
Henke s i m i l a r l y p o s tu la te s a c lo s u re due t o a downward s h i f t i n p o s itio n
o f th e h e a r t and th e hilum of th e lu n g s r e s u l t i n g frcm th e ex p an sio n o f
th e lu n g s .
T h is oau ses a tw is ti n g o f th e duotus whioh m o d ifie s th e en ­
tra n c e o f th e duotus in to th e a o r ta and h in d e rs th e blood flo w w ith in th e
d u o tu s .
Schanz lik e w is e assumed t h a t a s h i f t i n g in th e to p o g rap h y o f th e
th o ra o ic v is c e r a a t th e moment o f th e f i r s t i n s p i r a t i o n was re s p o n s ib le
f o r th e c lo s u r e o f th e d u c tu s .
The h e a r t moves av/ay from th e v e r t e b r a l
oolumn and s in k s w ith th e diaphragm ; th e hilu m o f th e lu n g i s d is p la c e d
and moves forw ard t o occupy th e c e n te r of th e th o ra x .
s e r t i o n o f th e d uotus in to th e a o r ta i s th u s m o d ifie d .
The an g le o f i n ­
T his change
alo n g w ith th e p re s s u re e x e r te d by th e p e ric a rd iu m o au ses th e c l o s u r e .
-9 4 -
S trassm ann d id n o t t h in k t h a t th e d e sc e n t o f th e diaphragm caused
o lo s u re o f th e d u c tu s , n o r t h a t th e p e ric a rd iu m is s tro n g enough t o p u l l
on th e d u ctu s and cau se k inking*
Strassm arm d e s c rib e d th e p e rio a rd iu m
a s s a c - lik e and moving w ith e v e ry change i n p o s iti o n o f th e h e a r t and
lungs and th e r e f o r e u n ab le t o e f f e o t th e c lo s u r e o f th e duotus*
S o h arfe
a ls o d i s c r e d i t s th e im portance o f a to p o g ra p h ic s h i f t a s a f a c to r i n th e
c lo s u re because o f i t s in co n stan cy *
K i r s t e i n m s co n v in ced however t h a t a change i n th e p o s itio n o f th e
h e a r t and s h i f t i n g o f th e o r ig i n o f th e g r e a t v e s s e ls o c cu rred a t th e
f i r s t b re a th *
U n til b i r t h th e diaphragm was h ig h ; a t th e f i r s t b r e a th
i t became deeper and p u lle d th e p e ric a rd iu m a lo n g w ith i t so t h a t th e
apex o f th e h e a r t was s h if te d from th e l e f t , tow ard th e r i g h t , to th e
m id lin e o f th e body*
As th e stern u m r i s e s , th e apex o f th e h e a r t i s
moved v e n t r a l l y b u t th e w a ll o f th e th o ra x rem ain s i n p o s i t i o n .
The
h e a r t r o t a t e s , th e l e f t v e n t r i o l e moves f u r t h e r forw ard and th e pulmonary
o r ig in o f th e duotus i s s h i f t e d more t o t h e 'r i g h t and p o s t e r i o r l y th u s
c a u sin g th e pulm onary o r ig i n and a o r t i c e n tra n o e o f th e duotus t o move
c lo s e r tow ard each o th e r .
S in ce th e v a s c u la r a ro h form ed by th e pulmonary
a r t e r y and d uotus i s u n ite d a t b o th ends marked b en d in g th e r e f o r e o c cu rs,
b u t n o t in th e same sense a s t h a t p o s tu la te d by W alkhoff*
Forbes p o s tu la te d a f i b r o s i s t h a t was due to a change i n p o s itio n o f
th e ductus w ith th e o n s e t o f r e s p ir a ti o n *
L inzenm eier s im i l a r l y p o s tu la te d
a th io k e n in g in th e m iddle o f th e d u o tu s, c o n s t r io tin g th e lumen somewhat*
The lumen d id n o t e n t i r e l y d is a p p e a r s in c e th e th ic k n e s s o f th e w a ll o f th e
ductus i s g r e a t enough to r e s i s t th e e f f e c t s o f r o t a t i o n and bending*
th e o ry i s s im ila r to t h a t o f Schanz who m a in ta in e d t h a t th e k in k in g was
This
-9 5 -
in c re a s e d th ro u g h th e d ra g o f th e p e ric a rd iu m a t th e a n g le o f k in k in g
o f th e d u c tu s .
The r o t a t i o n and k in k in g fo llo w in g th e change in p o s itio n
o f th e h e a r t and a r i s i n g a s a consequence o f th e f i l l i n g and ex p an sio n
o f th e lu n g s by th e f i r s t i n s p i r a t i o n was th e main f a c t o r in th e c lo s u re
o f th e d u c tu s a c c o rd in g to L in ze n m e ier.
T h is tu rn in g and k in k in g was
f a c i l i t a t e d by th e lo o se im bedding o f th e d u c tu s i n th e su rro u n d in g con­
n e c tiv e t i s s u e and a ls o by th e lo o s e c o n s tr u c tio n and e a s i l y y ie ld in g
s tr u c tu r e o f th e w a ll o f th e d u c tu s .
G raper t r i e d to determ ine th e ohange i n p o s itio n o f th e diaphragm
d u rin g th e f i r s t i n s p i r a t i o n .
lie observed t h a t th e o e n tr a l tendon b a r e ly
changed p o s itio n , only a s l i g h t f l a t t e n i n g o f th e a rc h o f th e diaphragm
o o c u rre d .
An in c re a s e i n th e s a g i t t a l d ia m e te r o f th e th o ra x th e r e f o r e
d id n o t cause an in c re a s e in th e bending o f th e a o r ta o r o f th e d u ctu s
b u t r e s u lte d o nly i n a s l i g h t f l a t t e n i n g of th e a rc o f th e d u c tu s .
As
a r e s u l t o f h is ex p erim en ts t e s t i n g th e d isp la ce m e n t and r o t a t i o n
t h e o r i e s , Grapor concluded t h a t th e c lo s u r e o f th e d u o tu s was n o t due
to a s h i f t i n p o s itio n o f th e d u c tu s d u rin g th e f i r s t i n s p i r a t i o n .
CQL1EBESSI0IJ OF THE DUCTUS ARTERIOSUS
Change i n form , r e l a t i o n , to p o g rap h y and even co m p ressio n o f
s t r u c t u r e s and organs w ith in th o c a v i t i e s o f th e body r e s u l t i n g from
th e e x p an sio n , u s u a lly r a p id , o f c e r t a i n o rgans - ”a c o m p e titio n f o r
space" a s d e s ig n a te d by iioback, lias been c r i t i c a l l y a n aly z e d in a tte m p ts
t o e x p la in c o n d itio n s a s found i n th e newborn and young i n f a n t .
The
ex p an sio n o f th e lungs and changes in th o r a c ic v is o e r a hase le d to v a rio u s
i n t e r p r e t a t i o n s o f some o f th e f a c to r s in v o lv e d in c lo s u re o f th e d u c tu s .
Vifalkhoff d e sc rib e d th e th o r a c ic c a v it y in th e newborn a s a v ery
-36 -
lim ite d space w hich in th e c o lla p s e d c o n d itio n i s com pressed a g a in s t
th e v e r t e b r a l column; th e diaphragm b ein g h ig h i n th e body c a v it y and
th e h e a r t i n a more h o r iz o n ta l p o s i t i o n .
T his changes c o m p le te ly when
r e s p i r a t i o n s e t s in ; th e lu n g s expand t o more th a n double t h e i r farm er
s iz e and p u l l upon th e pulm onary a r t e r y and th e a n g le o f e n tra n c e of
i t s b ra n c h e s .
The p o s t e r i o r co u rse o f th e s e b ran ch es i s s h i f t e d and
p u lle d l a t e r a l l y le a d in g to a lo w e rin g o f th e b e g in n in g o f th e ductus*
A ccording t o ilenke, how ever, p r e s s u r e on th e 7 /a ll o f th e d u o tu s by th e
a o r ta le a d s to com pression of th e s id e w a ll o f th e duotus and i t s sub­
seq u e n t c l o s u r e .
S tie n o n a ls o assumed t h a t th e d u o tu s was s u b je c te d to
a l a t e r a l p re s s u re by th e a o r t i c isth m u s a s i t d i l a t e s .
T h is le a d s to
com pression and c lo s u re of th e d u c tu s where i t i n s e r t s in to th e w a ll o f
th e a o r ta by a fo rc e t h a t i s p r o p o r tio n a l t o th e blo o d p re s s u re in th e
a o r t i c isth m u s.
S tie n o n i n agreem ent w ith S trassm ann f in d s t h a t a d i s ­
placem ent of th e th o r a c ic organs a t th e o n se t o f r e s p i r a t i o n does n o t
e f f e c t th e c lo s u r e o f th e duotus a s o th e rs have assum ed.
Uoback d is c u s s e d th e e f f e c t s o f t h i s "C o m p etitio n f o r Space" on th e
thymus and th e changes i t undergoes a t b i r t h and in th e new born.
Ke
found t h a t i t s change from th e b ro ad o r f e t a l ty p e t o th e e lo n g a te d or
moulded ty p e in th e liv e b o r n depended upon th e e s ta b lis h m e n t o f r e s p i r a ­
t i o n and th e expansion o f th e lu n g s .
The thymus i s com pressed l a t e r a l l y
by the expanding lu n g s and may ex ten d p o s t e r i o r l y to such an e x te n t t h a t
th e s t r u c tu r e s th e r e a re com pressed.
G raper a ls o d e s o rib e d th e changes
i n form t h a t th e thymus undergoes d u rin g th e e s ta b lis h m e n t o f r e s p i r a t i o n
as r e s u l t i n g in a d ecrea se in i t s l a t e r a l e x t e n t .
S in ce th e h e a r t shape
i s f ix e d , when i t moves th e apex moves more a n t e r i o r l y and th e sternum
-97 -
more s u p e r io r ly so t h a t th e space betw een th e a n t e r i o r c h e s t w a ll and
g ro a t v e s s e ls i s deepened.
C o n tra ry to th e o p in io n o f Hoback, G raper
b e lie v e d t h a t th e thym us, a p l a s t i c organ i s " p u lle d in to t h i s space"
th u s making u se o f t h i s com plem entary space and le a d in g t o th e c r e a tio n
o f a new complementary space by th e forw ard movement of th e p le u r a .
G raper f a i l e d however to n o tic e th e r e l a t i o n s h i p betw een th e thymus,
l o f t lu n g and ductus a r t e r i o s u s .
The p o s t e r io r s u rfa c e o f th e thymus
i s grooved by th e s e s tr u c tu r e s w ith w h ich i t comes in c o n ta c t.
The im­
p re s s io n s caused by th e g r e a t
v e s s e ls o f th e h e a r t and th e d u c tu s upon
th e thymus and m ed ial s u rfa c e
of th e
l e f t lu n g were a ls o o b serv ed by
Koback ( ’ 3 7 ), and a t t r i b u t e d to p re s s u re e x e rte d by th e se s t r u c t u r e s a s
th e y grew and expanded.
THEORIES OF CLOSURE OFTUB DUCTUS ARTERIOSUS
Changes in th e topography
o f th e
th o r a c ic o rgans have le a d t o th e
p ro m u lg atio n o f s e v e ra l th e o r ie s o f c lo s u r e .
O ther t h e o r io s s o le ly
based upon a n a to m ic a l f in d in g s , have a ls o been p u t f o r th to e x p la in th e
c lo s u re o f th e d u c tu s .
G undobin's summary c o n ta in s e x te n s iv e re fe re n c e
t o th e work of e a r l i e r in v e s t ig a to r s and t h e i r th e o r ie s a r e enum erated
and c a ta lo g u e d .
The v a rio u s th e o r ie s and t h e i r s u p p o rte rs (b a sed p a r t l y
upon th e c l a s s i f i c a t i o n o f Gundobin) w i l l now be d is c u s s e d .
(a ) Of h i s t o r i c a l i n t e r e s t .
S e v e ra l th e o r ie s were p u t f o r t h by H arvey, V a te r, B e rn d t, King
and Chevers t h a t a re o f h i s t o r i c a l i n t e r e s t o n ly ,b e c a u se o f th e many
in a c c u ra c ie s i n a n ato m ica l o b s e rv a tio n upon w hich th e y have been b a se d .
O thers have assumed t h a t th e fo rm a tio n o f a throm bus i n th e lumen i s
re s p o n s ib le f o r i t s c lo s u r e .
V a te r d e s c rib e d th e fo rm a tio n o f a d e f i n i t e
" sto p p in g su b sta n c e" b u t H a lle r on th e o th e r hand m a in ta in e d t h a t th e
-9 8 -
c lo s u re was due t o e. "bloody polypous m ass11*
(b ) Thrombus fo rm atio n *
Trew c o n sid e re d a p a r t i a l change o f th e c o m p o sitio n o f th e w a ll o f
th e d u ctu s to be th e m ain f a c t o r i n th e c lo s u re o f th e d u o tu s ,
C r u v e ilh ie r u sed a com bination o f two th e o r ie s t o d e s o rib e th e c lo s u r e ;
pseudomembranous ad h esio n s and o c c a s io n a lly throm bus fo rm a tio n a s th e
d i r e c t o a u s a tiv e fa c to rs *
R auchfuss however found o n ly tw elve throm bi
in 1400 cases*
(o ) Inflam m atory changes*
B ernutz and Henoch u t i l i z e d ev id en ce o f in flam m ato ry change a s a
b a s is f o r t h e i r t h e o r i e s .
They m a in ta in e d t h a t th e s e changes were cau sed
by i r r i t a t i o n o f th e w a ll,
(d) S h i f t i n to p o g ra p h y .
Changes ta k in g p la c e in th e c i r c u l a t i o n o f th e lu n g s , h e a r t , la r g e
blood v e s s e ls and p a r t l y in th e d u ctu s w ith th e o n s e t o f r e s p i r a t i o n and
le a d in g t o c lo s u re have been p o s tu la te d by H a lle r , Senac^ Hunauld, B e rn a rd ,
Sohumayer, W alkhoff, Landau, Sohanz, d eC rech io , B ie d e r t, V ogel, L in zen m eier,
G rap er, Henke, and Nobaok,
W alkhoff a s c r ib e s to th e a n t e r i o r s h i f t o f th e h i l u s o f th e lung
d u rin g th e o n s e t o f r e s p i r a t i o n a p u ll on th e a o r t i c e n tra n c e o f th e
ductus*
A ccording to t h i s a u th o r a s tro n g e r a rc h in g o f th e a o r t a and
ben d in g and change i n th e p o s itio n o f th e d u ctu s o c cu rs a s a r e s u l t o f
th e change in p o s itio n o f th e h e a r t and th e lo w e rin g o f th e diaphragm .
B ernard d e s c rib e d th e s h i f t in th e pulmonary a r t e r y a s b e in g p o s t e r i o r l y
un d er th e a o r t i c a rc h and th u s com pressing th e d u c tu s .
T h is e x p la n a tio n
a p p a r e n tly has been based upon in& ocurate o b s e rv a tio n s i n th e l i g h t of
th e f in d in g s i n our la b o ra to ry *
99-
Schanz based h is th e o ry p r im a r ily upon a s h i f t in th e th o r a c ic
s tr u c tu r e s b u t combined w ith t h i s s h i f t s e v e r a l o th e r f a c t o r s i n s t r u ­
m en tal in c a u s in g c lo s u r e .
A ccording t o him th e th o ra x o f a o h ild t h a t
has n o t b re a th e d i s s m a ll, th e diaphragm v ery h ig h and th e h e a r t in a
more h o r iz o n ta l p o s itio n th a n in th e a d u l t .
The a o r t i c a rc h i s more
tr a n s v e r s e ly s i t u a t e d and f ir m ly fix e d t o th e v e r t e b r a l colum n, th e d u ctus
opening in to th e a o r ta a t t h i s p la ce o f f i x a t i o n .
The p e r i c a r d i a l sac i s
a tta c h e d to th e ro o t o f th e g r e a t v e s s e ls a t th e o r i g i n o f th e d u ctu s and
a n t e r i o r l y and i n f e r i o r l y to th e sternum and diaphragm .
W ith ex p an sio n o f
th e lu n g s th e diaphragm i s drawn down and th e sternum r a is e d th u s i n ­
c r e a s in g i t s d is ta n c e a n t e r i o r l y from th e v e r te b r a l colum n.
The h e a r t i s
p u lle d down and as i t becomes more v e r t i c a l i t changes th e p o s it io n of th e
du ctu s w hich th e r e f o r e undergoes a c ti v e s tr e to h in g d u rin g th e ex p an sio n of
th e c h e s t.
The change
in
course o f th e d u ctu s and i t s m e c h a n ic a l c lo s u r e
due to
p u llin g upon i t i s
th e r e f o r e due to a com bination o f th r e e f a c t o r s ;
1 . th e
p u l l a n t e r i o r l y by
th e stern u m . 2 . th e lo w erin g o f th e diaphragm ,
and 3 .
th e p eric ard iu m p u llin g on th e e n c ir c li n g p la c e o f th e p e ric a rd iu m
on th e d u o tu s .
G raper a ls o p o s tu la te d a s h i f t in p o s itio n o f th e b a s a l
p o r tio n o f th e lie a rt le a d in g to s tr e tc h i n g o f th e a o r ta and a rc h of th e
d u o tu s .
The s h i f t in p o s itio n o f th e ductus a c c o rd in g to Henke, o c cu rred
in a downward m anner, th e h e a r t and hilum o f th e lu n g s move down due to
th e ex p an sio n o f th e lu n g s and cause a tw is tin g o f th e d u o tu s and t h e r e ­
fo r e h in d ra n c e to th e flo w o f b lo o d .
Faber p o s tu la te d a th e o ry of c lo s u r e
t h a t i s s im ila r to t h a t o f Henke i n t h a t th e c lo s u r e i s due to a s t r e to h in g
o f th e v e s s e l r e s u l t i n g from a p re s s u re c re a te d by th e l e f t pulm onary a r t e r y
a s i t g r a d u a lly f i l l s w ith b lo o d .
-1 0 0 -
(e ) C om pression by l e f t b ro n ch u s, pulm onary a r t e r y , e t c .
S h if tin g i n th e to p o g rap h y o f th e ductus and a r e s u l t i n g com pression
has a ls o form ed th e b a s is o f o th e r th e o r ie s o f c lo s u r e o f th e duotus
a rte rio s u s .
B ernard (1733) d e sc rib e d th e c lo s u r e a s due t o a com pression
by th e pulm onary tru n k w hich he th o u g h t was p u lle d backw ard and to th e
r i g h t under th e a o r t i c a r c h .
H is o b s e rv a tio n s have proven to be in a c o u r-
a t e and th e r e f o r e h i s th e o ry in c o r r e c t and u n te n a b le .
King assumed t h a t
d i l a t i o n o f th e l e f t bronohus le d to com pression and c lo s u r e .
T his to o
has been d isp ro v ed an d d is c a rd e d s in c e th e bronchus i s in c a p a b le o f s u f ­
f i c i e n t e x p a n s io n .
th e a o r t a .
Henke assumed a com pression o f th e d u c tu s w a ll by
T h is o c cu rred because of an in c re a s e in blo o d flo w to th e
lungs and d e c re a se tlirough th e d u c tu s .
The p re s s u re o f th e a o rta , on
th e w a ll o f th e d u ctu s a t th e low er an g le where th e y come to g e th e r cau ses
th e c lo s u r e o f t h i s o p en in g .
S te in o n a g re e s w ith Henke t h a t o lo s u re is
due to com pression by th e isthm us o f th e a o r ta and t h i s co m p ressin g fo rc e
i s p r o p o r tio n a l t o th e blood p re s s u re in th o isthm us o f th e a o r t a .
Chevers had c r e d ite d th e loop of th e r e c u r r e n t la r y n g e a l n erv e w ith
s u f f i c i e n t s tr e n g th to cause com pression o f th e d u c tu s .
S ubsequent i n ­
v e s t i g a t o r s have shown t h i s to b e a f a l s e .a s s u m p t i o n .
( f ) E xpansion o f lu n g s .
Many o f th e above-m entioned in v e s t ig a to r s have u t i l i z e d th e ex p an sio n
o f th e lun gs a s th e b a s is f o r p o s tu la tin g a s h i f t in to p o g rap h y o f th e
th o r a c ic v is o e r a .
K elka, S tien o n and D ragendorf have used th e ex p an sio n
o f th e lungs t o e x p la in an in c re a s e d demand f o r b lo o d by th e lu n g s and
th e r e f o r e a d e c re a se in flo w thro u g h th e ductus a s b e in g in s tru m e n ta l in
i t s c lo s u r e .
■101.
Ivielka u s e s n o t o n ly th e com pressing fo rc e o f th e isthm us of th e
a o r t a b u t a l s o th e expanded pulm onary a r t e r y .
As a r e s u l t o f a change
in b lo o d p re s s u re r e l a t i o n s h i p s a t b i r t h , th e expanded a o r t a and p u l­
m onary a r t e r y compress th e d uctu s w hich i s betw een them.
A o rta
U itnm s d e x te r
A rtPtia fu l
lltO
U
H
IlS
K am u- hiiiM or
A Mi,
K
1.
d e x to i
A1)1). 2.
F ig , 3 1 ,
Melka
S tie n o n a l s o found a c o n sid ere.b le in c re a s e in blood p re s s u re in th e
a o r ta w ith th e o n set o f r e s p i r a t i o n sin c e a la r g e amount o f b lo o d a ls o
flo w s i n t o th e lu n g s th ro u g h th e pulm onary a r t e r y .
His th e o r y o f c lo s u r e
i s s im ila r t o t h a t o f Lielka ex cep t t h a t th e p re s s u re i s e x e r te d on th e
a o r t i c e n tra n c e o f th e d uotus by th e su rro u n d in g v e s s e ls ,
(g ) F a l l i n blo o d p r e s s u r e .
O ther w orkers have a s c r ib e d th e c lo s u re of th e ductus t o a f a l l
r a t h e r th a n t o a r i s e in blood p r e s s u r e ,
S c h u ltz e p o in ts o u t t h a t th e
d u ctu s e n te r s th e a o r t i c a rc h a f t e r i t s branohes have been g iv e n o f f and
th e r e f o r e th e blood p re s s u re in th e d escending a o r ta betw een th e e n tra n c e
-1 0 2 -
o f th e duotus and th e l a s t bran ch o f th e a o r t i c a rc h i s low er th a n in
th e pulmonary tr u n k .
The blood w i l l th e r e f o r e flow from th e pulm onary
tru n k th ro u g h th e d u otus in to th e a o r ta to e q u a liz e th e p r e s s u r e .
The
isthm us o f th e a o r ta (betw een th e e n tra n c e o f th e ductus and th e sub­
c la v ia n a r t e r y ) has a h ig h e r p re s s u re a f t e r b i r t h due t o th e c lo s u r e o f
th e d u c tu s .
T h is change in blood p re s s u re S c h u ltz s b e lie v e s o ccu rs a t
b i r t h because o f th e change in blood c i r c u l a t i o n and h y p e rtro p h y o f th e
le f t v e n tric le .
The blo o d p re s s u re f a l l is m ost m arked in th e pulm onary
tr u n k a t b i r t h .
T h is i s due to com plete ex p an sio n o f th e lu n g s w hioh now
d i v e r t a la rg e volume o f blood where p re v io u s ly th e y had ta k e n up b u t
l i t t l e b lo o d .
The flow th ro u g h th e d u ctu s th e r e f o r e d e c re a se s and in t u r n
c au ses a f a l l i n p re s s u re i n th e a o r t a .
The work o f th e r i g h t v e n t r i c l e
rem ains l i g h t w ith th e o n s e t o f r e s p i r a t i o n , th e r e f o r e th e pulm onary
p re s s u re rem ains low .
As long a s t h e l o f t v e n t r i c l e f a i l s to r a i s e th e
p re s s u re o f th e descen d in g a o r ta above th e p re s s u re in th e pulm onary a r t e r y
th e d uctu s rem ains p a te n t a s in th e f o e t a l c o n d itio n ,
A c r i t i c a l s ta g e
a r i s e s however i n w hich an e q u ilib riu m i s form ed when th e blood column
s ta n d s s t i l l and c lo s u r e o c c u rs .
S ch u ltze combines t h i s f a l l in p re s s u re
w ith a p o s s ib le throm bus fo rm a tio n a s th e f a c t o r s making p o s s ib le a con­
t r a c t i o n o f th e w a lls o f th e d u ctu s upon a column o f blo o d t h a t i s p r a o t i c a l l y s ta n d in g s t i l l .
The s ta g n a tio n o f th e blo o d flow oocurs when th e
p re s s u re d if f e r e n c e betw een th e pulmonary a r t e r y and a o r ta is zero and
th e blo o d p re s su re in b o th v e s s e ls i s g r e a tly lo w ered .
T h is p e rio d of
stoppage i n flow accom panied by low ered p re s s u re i s supposed t o l a s t f o r
s e v e ra l h o u rs o r even d a y s.
The d e crea se in pulmonary p re s s u re th e n r e ­
m ains c o n s ta n t w h ile t h a t o f th e a o r ta in c re a s e s w ith h y p e rtro p h y o f th e
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l e f t v e n tric le .
Complete c lo s u re o f th e ductus th e r e f o r e o ccu rs only
when th e b lo o d flo w in i t i s sto p p ed and ta k e s p la c e acc o rd in g t o th e
e x p la n a tio n by S c h u ltz e " d u rin g t h i s p e rio d th e c lo s u re of th e d u ctu s
a r t e r i o s u s i s so fa v o ra b le , when, as i s v e ry p ro b a b le , b u t my fin d in g s
th ro u g h a n a to m ic a l re s e a rc h does n o t show i t , th e c o n t r a c t i l e elem en ts
in th e f u l l - t e r m f e tu s have more fo rc e th a n th e e l a s t i c e le m e n ts, d i f ­
f e r i n g from t h a t o f o th e r a r t e r i e s . "
Zuntz and Cohnheim 's o b s e rv a tio n s a r e s im ila r t o th o se o f S c h u ltz e
in t h a t th e y to o m a in ta in t h a t th e v e l o c i t y o f flow i n th e duotus b e oomes v e ry s m a ll, t h e o r e t i c a l l y a lm o st z e r o .
S im ila r ly , K irB te in b e­
lie v e s t h a t th e in c re a s e i n a o r t i c p re s s u re a g a in s t th e lower w a ll o f
th e d u c tu s i s so g r e a t t h a t th e ductus c an n o t now r e s i s t th e in c re a s e d
p re s s u re o f th e a o r t a because o f th e f a l l in p re s su re w ith in th e d u c tu s
its e lf.
Thoma however m a in ta in e d t h a t changes in blood p re s s u re were n o t
th e m ost im p o rta n t f a c to r s a f f e c t i n g c lo s u r e o f th e d u c tu s .
The d is a p ­
pearance o f th e blood flow i s m ost im p o rta n t f o r a t t h i s tim e , r e g a r d le s s
o f th e p r e s s u r e , a s te a d y c o n tr a c tio n o f th e m edia s e ts i n .
to have shown t h i s by means o f v e ry f in e m easurem ents.
He claim s
I f th e narrow ing
o f th e d u ctu s does n o t o ccu r, s ta g n a tio n o f th e blood flo w oocurs a g a in
and th e lumen narrow s to a id th e grow th o f c o n n e c tiv e t i s s u e .
Wien t h i s
narrow ing o f th e lumen o f th e duotus becomes so s n a i l t h a t th e p re v io u s ly
s ta g n a te d blood flow s th ro u g h a g a in a t i t s form er v e l o c i t y , so t h a t th e
o ld p r o p o r tio n betw een th e lumen and th e b lo o d v e lo c i ty i s a g a in re a c h e d ,
th e c o n tr a c tio n o f th e media and th e grow th o f th e in tim a r e s u l t s in what
he c a l l s "com pensating e n d a r t e r i t i s " .
The c lo s u re th e r e f o r e is due t o a
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s t a n d s t i l l o f blood i n th e d u c tu s p lu s a c o n tr a c tio n o f th e m u s c u la tu re .
H am ilton, Woodbury and Woods do n o t b e lie v e t h a t changes in p re s su re
o r flow a re f a c to r s i n i t s c lo s u r e f o r th e y f in d t h a t th e "low ered p u l­
monary r e s i s t a n c e , upon th e e s ta b lis h m e n t o f a n e g a tiv e in tr a t h o r a c ic
p re s s u re must n e c e s s a r ily cause th e d uotus stream t o flow from th e a o r ta
t o th e pulmonary a r t e r y . "
"The stoppage o f th e stre am and c lo s u re o f th e
d u ctu s a r t e r i o s u s i s n o t a n in h e re n t ten d en o y o f th e ductus a r t e r i o s u s to
c lo s e a g a in s t h y d r o s ta tic f o r c e s b e c a u se , i f h y d r o s ta tic fo rc e s a re la rg e
enough a s in c o n g e n ita l s te n o s is o f th e a o r t i c or pulm onary r i n g , th e
d u ctu s may rem ain p a te n t th ro u g h l i f e . "
"There i s n o t a g ra d u a l dim inu­
t i o n o f th e d if f e r e n c e of h y d r o s ta tic p re s s u re a t th e two ends o f th e duc­
t u s because th e system ic an d pulmonary p re s s u re s in a l l p r o b a b i lity grow
a p a r t a s th e c h e s t expands and th e sy stem ic b lo o d p re s s u re b u ild s u p ."
The ductus o r d i n a r i l y c lo s e s a g a in s t and in s p it e o f t h i s stre am , because
i t i s i t s n a tu re t o do t h a t p a r t i c u l a r th in g i f th e fo rc e o f th e stream
i s n o t to o g r e a t ."
(h ) V alve a c tio n and changes i n blood p r e s s u r e .
S e v e ra l in v e s t i g a t o r s have combined th e s e changes in blood p re s s u re
w ith a v a lv u la r a c ti o n on th e p a r t o f th e d u c tu s .
T his has been s tro n g ly
d is p u te d however, and a t p r e s e n t i s n o t w id e ly s u p p o rte d .
Strassm ann was
th e forem ost proponent o f th e th e o ry t h a t th e r e l a t i v e p re s s u re s in th e
a o r ta and pulmonary a r t e r y became re v e rs e d im m ediately a f t e r th e lu n g s
a re i n f l a t e d .
The blo o d th e n a tte m p ts to p a ss from th e a o r ta t o th e p u l­
monary a r t e r y and th u s as th e p re s s u re in o re a s e s in th e a o r t a , th e u p p er
a n g u la r l i p (v alv e o f Strassm ann) o f th e a o r t i c e n tra n c e o f th e duotus
becomes p re s s e d inw ard upon i t s e l f and th u s o c clu d e s th e lum en.
Strassm ann
co n sid e re d t h i s v a lv e -sh a p e d s t r u c tu r e t o be a f u n c tio n a l v a lv e p r o je c tin g
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over th e a o r t i c e n tra n o e .
R oeder and Fromberg claim ed t h a t th e v a lv e was
p r e s e n t a s Strassm ann d e sc rib e d i t .
was n o t e asy to f i n d .
Haberda however m a in ta in e d t h a t i t
I t s p re sen c e h as b een d is p u te d by S c h a rfe ,
L in zen m eier, K i r s t e i n , Sehanz, S o h u ltz e , and Gundobin; th e g e n e ra l
concensus o f o p in io n b ein g t h a t i t i s a n a r t e f a c t and th e r e f o r e h is
th e o ry u n te n a b le .
In t h i s la b o r a to r y , e x am in atio n o f specim ens has
f a i l e d t o re v e a l in a s in g le in s ta n c e , th e p re sen c e o f a v alv e such a s
p o s tu la te d by S trassm an n .
( i ) Llusoular c o n tr a c tio n .
Blood p re s s u re changes combined w ith o th e r f a c t o r s such a s c o n tr a c tio n
o f th e w a lls o f th e duotus have formed th e b a s is o f some e x p la n a tio n s o f
th e c lo s u re of th e d u c tu s.
Czermak, K iw isch and V irchow have r e f e r r e d to
a m u scu lar c o n tr a c tio n o f th e w a ll a s c a u s in g c lo s u r e .
Langer d id n o t b e ­
lie v e in th e im portance o f th e c i r c u l a t o r y changes a t b i r t h b u t r a t h e r in
th e in h e re n t s tr u c tu r e o f th e d u c tu s , to q u o te , "W hether and how f a r
c lo s u r e o f th e p la c e n ta l c i r c u l a t i o n , th e b e g in n in g o f r e s p i r a t i o n , l i k e ­
w ise th e movement o f th e diaphragm m e c h a n ic a lly in flu e n c e s th e in v o lu tio n
o f th e f o e t a l r i g h t a o r t i c a rc h (D uctus B o t a l l i ) i s n o t y e t s u f f i c i e n t l y
c le a re d u p , t h a t i t i s however n o t th e changed m e ch a n ic al c i r c u l a t i o n r e ­
l a t i o n s w hich b r in g about i t s c lo s u r e i s shown by th e o r i g i n o f th e p e­
c u l i a r s t r u c t u r a l r e l a t i o n s h i p o f th e a r t e r i a l v e s s e l (d u c tu s a r t e r i o s u s )
compared to th e a o r ta and pulm onary a r t e r y ; beoause o f th e s e p e c u l i a r i t i e s
th e l a t e r in v o lu tio n o f th e v e s s e l i s a lr e a d y p refo rm ed ."
Thoma a ls o p o s tu la te d a c tiv e c o n tr a c ti o n o f th e m u so u latu re o f th e
d u ctu s alo n g w ith h i s "com pensatory e n d a r t e r i t i s " .
K i r s t e i n , who does n o t
a g re e w ith Thama, based h is th e o ry upon i n j e c t i o n e x p e rim e n ts.
A t th e
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f i r s t norm al b r e a th th e th o ra x i s f i r s t expanded
ex p a n sio n o f th e lu n g s .
and th e n fo llo w e d by-
T his le a d s to a bending o r k in k in g o f th e duotus
in th e same sen se a s t h a t p o s tu la te d by W alk h o ff.
The c lo s u re o o o u rred
f i r s t i n th e m iddle and th e n proceeded tow ard b o th e n d s .
m a riz e s th e f a c to r s
K irs te in
sum­
c au sin g c lo s u re a s fo llo w s*
1 . An e q u a liz a tio n o f a o r t i c and pulm onary p re s s u re s and c o n tr a c tio n
of th e w a ll of th e d u ctu s sim u lta n e o u s ly or im m ed iately a f t e r .
2 . The e la s tic o ^ n u s c u la r elem ents i n th e in tim a o f th e d u c tu s de­
v e lo p d u rin g pregnancy i n an o rd e rly m anner.
3 . The change in p o s itio n of th e h e a r t due t o th e f i r s t b r e a th
which cau ses an a rc h in g o f th e pulm onary p o r t i o n ,
4 . The d u ctu s valve a t th e a o r t i c e n tra n c e o f th e d u c tu s .
5 . The com pensatory e n d a r t e r i t i s .
Haberda a ls o p o s tu la te d an e q u a li z a tio n in b lo o d p re s s u re betw een
th e pulmonary a r t e r y and a o r ta t h a t ta k e s some tim e t o be re a c h e d . D uring
t h i s tim e some blood p a sse s th ro u g h th e duotus w hich c o n tin u e s t o con­
t r a c t more and more u n t i l a t th e moment o f eq u al p re s s u re th e c i r c u l a t i o n
s to p s and th e lumen d is a p p e a rs ,
b u t ilaberda d id n o t b e lie v e t h a t th e
a c ti v e c o n tr a c tio n of th e m u scu latu re o f th e ductus was s u f f i c i e n t to
cause com plete c lo s u r e ; an opportune moment m ust a ls o e x i s t .
L inzenm eier
a ls o observed a s tro n g , p ro g re s s in g c o n s t r i c t i o n w hich r e s u lte d from th e
s lig h t r o t a t i o n o f th e a x is of th e d u ctu s due t o a d isp la c e m e n t of th e
h e a r t and th e f i l l i n g o f th e lu n g s .
The c o n s t r i c t i o n o f th e d u c tu s f o l ­
lowed th e drawing to g e th e r of i t s ends and r o t a t i o n o f i t s long a x is on
i t s e l f because o f f i x a t i o n a t th e e n tra n c e in to th e a o r t a .
C o n tra c tio n
o f th e s p i r a l l y run n in g m usole bu n d les h e lp s in k in k in g and s t a b i l i z i n g
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th e d u c tu s .
(See F ig . 18, page 5 0 ) .
An e x tre m ely m arked c o n t r a c ti o n
o f th e w a lls o f t h e d u ctu s w hioh o ccu rred a t b i r t h and was n o t r e p e a te d
a g a in , fo rc e d th e blo o d in to th e pulmonary b ran ch es a c c o rd in g t o L andau.
The sm all amount o f c o n t r a o t i l e and e l a s t i c elem en ts o f th e w a ll o f th e
d u ctu s c o n tra c te d a t th e same moment i n w hich th e blood was l o s t and th u s
p re v e n te d a f u r t h e r flo w .
The th e o ry o f c o n tr a c tio n o f th e muscle w a lls has a l s o had i t s op­
p o n e n ts .
S tie n o n , S c h u ltz e , Z ieg en sp eck , C o h n stein and Z u n tz, opposed
t h i s th e o ry because th e y d id n o t th in k t h a t th e w a ll o f th e d uctus was
s tro n g enough in i t s e l f t o oppose th e h y d r o s ta tic p re s s u re o f th e column
o f b lo o d flow ing th ro u g h .
( j ) A c tiv e p r o l i f e r a t i o n , th ic k e n in g or s h r in k in g .
C hevers, Langer and R ok itan sk y a s c rib e d th e c lo s u r e to a th ic k e n in g
and s h rin k in g o f th e w a l l .
C hevers d e sc rib e d an in c re a s e d flo w i n t o th e
lungs an d le ss e n e d flo w th ro u g h th e ductus w hich now s h r in k s up and
g ra d u a lly c lo s e s b ecause o f i t s own e l a s t i c i t y .
A ccording t o R o k ita n sk y ,
an a o c e le r a te d p r o l i f e r a t i o n o f c o n n e c tiv e t i s s u e in th e w a ll o f th e
duotus accom plished th e c lo s u r e .
A c tiv e p r o l i f e r a t i o n o f v a rio u s elem ents i n th e w a ll h as form ed th e
#
b a s is o f o th e r t h e o r i e s .
C losu re a cco rd in g t o Baum garten, r e s u l t e d from
c e l l grow th o f th e e n d o th eliu m .
in te r n a aco o rd in g t o C o sta .
The h y p e rp la s ia o ccu rs in th e e l a s t i c a
G raper a ls o found t h a t a c ti v e h y p e rp la s ia
o f th e e l a s t i c a in te r n a o o c u rre d .
Haberda d e sc rib e d a new c o n n e c tiv e
t i s s u e fo rm a tio n an d grow th on th e f r e e o u te r s u rfa c e o f th e in tim a o r
th ro u g h th e e n d o th eliu m i n t o th e lumen.
B a rc la y , B a r c r o f t, B arron and F ra n k lin ( '3 8 ) a tte m p te d t o s tu d y i n sheep
th e c lo s u r e o f th e d u c tu s by means o f x -ra y s and found t h a t th e c lo s u r e
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does n o t o c cu r by means o f a sim ple c o n tr a c ti o n o f th e w a ll b u t by
c o n tr a c tio n o f in d iv id u a l lo c a l iz e d m uscle b u n d les w hich oause k in k in g
and t w i s t i n g o f th e lum en.
These c o n tr a c tio n s c o n tin u e f o r some tim e
a f t e r th e d u o tu s i s f u n c tio n a ll y c lo s e d .
These f in d in g s have been com­
p l e t e l y re p u d ia te d by th e a u th o rs i n a su b seq u en t p e rs o n a l com m unication.
POSTNATAL CLOSURE AND OBLITERATION
The v a rio u s th e o r i e s o f c lo s u r e o f th e d u ctu s w hich have been d i s ­
c u sse d do n o t e x p la in s a t i s f a c t o r i l y a l l th e f a c t o r s in v o lv e d i n i t s
c lo s u r e .
Idany o f th e s e th e o r i e s assume t h a t o lo s u re occurs a t th e moment
o f b i r t h when r e s p i r a t i o n commences w h ile o th e rs assume t h a t a p e rio d o f
tim e e la p s e s b e fo re c lo s u r e o c c u r s .
The lumen was wide open a f t e r two t o
th r e e d ay s, th e c o n tr a c tio n o c c u rrin g p o s t n a t a l ly a cc o rd in g t o G rap er.
S tie n o n found t h a t c lo s u r e o c cu rred a f t e r s ix to tw elv e d a y s.
A sm all
lumen e x is t e d i n th e d u c tu s f o r more th a n two weeks a c c o rd in g t o L an g er.
The p e rio d o f c lo s u r e e x ten d e d f o r s ix weeks a c c o rd in g t o E l s a s s e r .
G erard found a s h o r te r p e rio d ra n g in g betw een fo u r te e n and tw e n ty days
was n e c e s s a r y .
Haberda found t h a t th e g r e a te s t number o f specim ens were
c lo s e d a f t e r s i x weeks and i n a l l c a s e s a f t e r s i x m onths.
Melka observed
an i r r e g u l a r c r e s c e n t shaped lumen even a f t e r f iv e and te n m o n th s.
Weizmann found th e lumen s t i l l d is o e r n ib le even a f t e r e ig h ty y e a r s .
H ost o f th e i n v e s t i g a t o r s b e lie v e d t h a t p h y s io lo g ic a l c lo s u r e o c c u rre d
a t b i r t h o r s h o r t l y a f t e r , and a n a to m ic a l o b l i t e r a t i o n o c c u rre d d u rin g
a more e x ten d e d p e rio d ra n g in g from days t o y e a r s .
C h r is tie examined
558 norm al newborn in f a n ts and o b serv ed a ra p id and uniform tim e o f
c lo s u r e up t o a b o u t e ig h t weeks and th e n a m arked slo w in g .
88% o f th e
in f a n ts show c lo se d d u c tu s a t t h e end o f e i g h t w eek s. ( F ig . 24, page 6 3 ) .
B i l l a r d d e s c rib e d th e manner o f p o s tn a t a l a n a to m ic a l o b l i t e r a t i o n .
-1 0 9 -
The w a lls o f th e duotus become t h i c k e r and a c o n c e n tric h y p e rtro p h y
d ev elo p s in them w hich n arrow s th e lumen o f th e d uotus w ith o u t e f f e c t ­
in g i t s o u te r c irc u m fe re n c e .
When th e d uotus has undergone t h i s h y p er­
tro p h y and o b l i t e r a t i o n th e c e n te r c o n ta in s n o th in g more th a n a sm all
h o le .
P f e i f f e r m a in ta in e d t h a t th e o b l i t e r a t i v e p ro c e ss d id n o t p ro ­
ceed s t e a d i l y from day t o d a y .
R e tro g re s s io n o c o u rre d so t h a t c h ild re n
o f th e same age were n o t alw ays in th e same s ta g e .
PHYSIOLOGICAL CONSIDERATIONS OF BLOOD CIRCULATION
Study o f th e changes i n m orphology o f th e d u ctu s le d t o a b e t t e r
u n d e rs ta n d in g o f th e conoom m ittant changes r e s u l t i n g in th e p h y sio lo g y
o f th e c i r c u l a t i o n .
S e v e ra l th e o r i e s o f flo w e x i s t w hioh can be tr a c e d back t o th e
S a b a tie r sc h o o l which m a in ta in e d t h a t t h e two c a v a l stream s c ro s s e d in
th e r i g h t a tr iu m , w ith o u t m ix in g ; th e s u p e r io r c a v a l stream p a s s in g
th ro u g h th e t r i c u s p i d v a lv e t o th e r i g h t v e n t r i c l e and th e i n f e r i o r
c a v a l stream th ro u g h th e foram en o v a le t o th e l e f t v e n t r i c l e .
T h is
arran g em en t le d to a r i c h e r oxygenated blo o d su p p ly t o th e head and
upper e x tr e m itie s th a n t o th e r e s t o f th e body and th e r e f o r e r e s u l t e d
i n a more r a p id developm ent of th e s e p a r t s .
The Harvey-Pohlman sch o o l
on th e o th e r hand b e lie v e d t h a t th e two stream s were m ixed in th e r i g h t
a tr iu m .
A t p r e s e n t t h i s d i v e r s i t y of o p in io n s t i l l e x i s t s .
K ellogg
(1928) in je c te d p ig f e tu s e s and a s a r e s u l t o f h is fin d in g s su p p o rted th e
Harvey-Pohlman s c h o o l.
K ilia n b e lie v e d t h a t no m ixing o ccu rred becau se
th e r i g h t and l e f t v e n t r i c l e s a o co rd in g to h is o b s e rv a tio n s c o n tr a c te d
a t th e same tim e f o r c e f u l l y pumping th e b lo o d o u t w ith such speed t h a t
m ixing c o u ld n o t occur and th e r e f o r e a double c i r c u l a t i o n r e s u l t e d .
-1 1 0 -
As th e pulmonary c i r c u l a t i o n in c re a s e d th e flow th ro u g h th e duotus de­
c re a s e d u n t i l v e ry l i t t l e or no b lo o d f lowed th ro u g h , ftrenotally the greatest
p a r t of th e blood flow s th ro u g h th e d u c tu s and n o t tlirough th e r i g h t
and l e f t pulm onary a r t e r i e s (K iw isc h ).
The flo w from th e r i g h t v e n tr ic le
i s s tro n g e r because th e d uotus i s s h o r t e r and f l a t t e r th an th e ascen d in g
a o rta .
The a o r t i c e n tra n c e o f th e d u c tu s i s narrow ed so t h a t th e stream
from th e d u c tu s makes a n o tic e a b le a n g u la r movement th u s re d u c in g i t s
fo rce .
ICiwisch f u r t h e r employs th e e x p an sio n o f th e lungs and c a p i l l a r y
netw ork to suck in blood an d a i r and th u s w iden th e pulmonary a r t e r i e s
w hich i n tu r n r e s u l t s in a lotvered r e s i s t a n c e t o blood flo w th a n in the
descending a o r t a .
This d is p la c e s a g r e a t e r q u a n tity o f blo o d tow ard th e
pulm onary b ranches and away from th e d u ctu s and lo a d s to a rin g -fo rm e d
c o n tr a c tio n o f th e d u c tu s .
S ince th e u m b ilic a l v e s s e ls have a ls o been
c u t th e r e i s a d ecrea se d fo rc e o f flo w in th e d escen d in g a o r t a ; th e l e f t
v e n t r i c l e re c e iv e s more b lo o d from th e a triu m and lu n g s and sends more
in to th e a o r ta and t h e r e f o r e l e s s in to th e d u c tu s .
S c h u ltz e a ls o su p p o rte d th e H arvey-kohlman th e o r y of m ixing o f th e
two c a v a l stream s in th e r i g h t a tr iu m .
H is d e s c r ip ti o n o f th e changes in
blood flow i s s im ila r t o t h a t o f K iw isch b u t th e p re s s u re r e la t io n s h ip s
d i f f e r a s p re v io u s ly d e s c r ib e d .
The pulm onary a r t e r i e s undergo th e
m ost marked f a l l in p re s s u re sin c e th e y a re opened wide by th e in c re a s e d
n e g a tiv e p re s s u re o f th e th o r a x .
Thoma assumes t h a t th e low ered p re s s u re
i s due t o a slow ing o f th e blood flo w w hich o o cu rs when th e h e a r t d riv e s
a sm a lle r volume of b lo o d th ro u g h th e in c r e a s e d r e s is ta n c e o f th e c a p i l l a r y
bed.
Sohanz on th e o th e r hand s t a t e s t h a t an in c re a s e in th e b lo o d column
o ccu rs due t o th e w idening o f th e re g io n of flo w and th e r e f o r e th e work o f
-1 1 1 -
th e h e a r t in c re a s e s le a d in g t o h y p e rtro p h y o f th e l e f t v e n t r i c l e ,
Koeder d e s c rib e d th e r o le o f th e d u o tu s d u rin g developm ent, b o th
b e fo re and a f t e r b i r t h , a s a n e q u a li z e r o f t h e h ig h e r p re s s u re end
m arked p re s s u re f lu c tu a tio n s i n th e a o r ta and pulm onary a r t e r y .
It
c a u se s r e v e r s a l o f th e f e t a l blood p re s s u re and th u s le a d s t o th e f o r ­
m a tio n o f a new, p h y s io lo g ic a l b lo o d p r e s s u r e d if f e r e n c e t h a t i s prom ptly
b ro u g h t ab o u t by th e d e f i n i t e s e p a r a tio n o f b o th stre am s o f flo w ,
S tie n o n
q u e s tio n s th e em ptying of th e d u ctu s fo llo w in g e x p an sio n o f th e lu n g s and
i t s su bsequent c o lla p s e .
T h is , to him , does n o t e x p la in th e sto p p ag e o f
th e c i r c u l a t i o n f o r tine a o r t i c o r i f i c e o f th e duotus rem ains open a t t h i s
tim e and a t th e pulm onary e x p an sio n in c re a s e d b lo o d w ould be 6ucked from
th e a o r ta in to th e duotus t o th e pulm onary a r t e r i e s .
He b e lie v e s e x ­
p a n sio n o f th e isthm us o f th e a o r t a and i t s p re s s u ro a g a in s t th e d u ctu s
c a u se s c lo s u r e ,
iie lk a does n o t a g ree w ith S tie n o n f o r th e d u o tu s c o n ta in s
much new ly formed c o n n e c tiv e t i s s u e a t t h i s p o in t and co m p ressio n would
t h e r e f o r e be v e ry d i f f i c u l t .
Iielk a fa v o rs an o p p o rtu n e moment o f m echani­
c a l c lo s u re when th e blood flo w s to p s b ecau se of a change in b lo o d p re s s u re
r e l a t i o n s in th e pulmonary a r t e r y and a o r t a r e s u l t i n g in an in c re a s e d
a o r t i c blo o d p r e s s u r e .
B o ttin g e r m a in ta in s t h a t th e qu io k flo w in g a o r t i c
stream a c t s a s a pump and p re v e n ts th e flow o f b lo o d from th e a o r ta in to
th e d u o tu s .
B atten a s c r ib e s a n o th e r f u n c tio n t o th e pulm onary c i r c u l a t i o n ;
t h a t o f a id in g in c lo s u re o f th e foram en o v a le .
As th e pulm onary c i r c u ­
l a t i o n in c re a s e s th e r e i s a p r o g r e s s iv e ly le s s e n e d com pensatory flo w
th ro u g h th e foram en o v ale whioh le a d s to i t s c l o s u r e .
The flo w th ro u g h
th e duotus i s eq u al t o t h a t o f th e isthm us o f th e a o r t a , th e pulm onary
c i r c u l a t i o n p la y in g a v i t a l r b le i n th e f e t a l c i r c u l a t i o n to m a in ta in th e
-1 1 2 -
b a la n c e d flow*
Since th e pulm onary c i r c u l a t i o n i s o p e ra tin g a t c a p a c ity
b e fo re b i r t h th e r e i s no n e c e s s ity f o r a la r g e in o re a s e i n volume o f th e
p o s tn a t a l pulm onary c i r c u l a t i o n a c c o rd in g to R a tte n .
H am ilton, Woodbury
and Woods d is a g re e w ith P a tte n f o r th e y f in d t h a t th e f e t a l pulm onary
flo w i s much s m a lle r th a n th e sy ste m ic , " t h a t th e f e t a l lu n g s r e c e iv e a
stre am o f blood la r g e enough t o m easure up to th e s iz e o f th e v e s s e ls
and i n c i d e n t a l l y t o su p p o rt r e s p i r a t i o n a f t e r b i r t h when so la r g e a
stream w ould seem t o be o u t o f a l l p ro p o rtio n t o th e m e ta b o lic n eed s o f
th e lu n g s ."
ONSET OF RESPIRATION
The e x p la n a tio n o f th e changes i n c i r c u l a t i o n has been based u s u a lly
upon changes ta k in g p la c e w ith th e o n s e t o f r e s p i r a t i o n and th e ex p an sio n
o f th e lu n g s .
King d e s c rib e d th e p r in c ip a l e f f e c t s o f th e f i r s t i n s p i r a ­
t i o n a s b e in g a g e n e ra l expansio n and e s p e c i a ll y o f th e lu n g s whioh was n o t
oom pleted u n t i l same tim e l a t e r ; th e diaphragm and h e a r t p u lle d down, th e
lu n g s expanded outw ards and th e l e f t bronchus re n d e re d more f u l l and te n s e
and r a i s e d .
A t th e some tim e th e d u c tu s i s drawn down w ith some fo rc e
c a u s in g i t to bend over th e l e f t bronchus i n a more o b liq u e d i r e c t i o n .
Virchow a g re e d w ith King re g a rd in g com pression of t h e d u c tu s by th e e x ­
p a n sio n o f t h e l e f t bronchus w ith th e f i r s t r e s p i r a t i o n w hioh th e o ry has
s in c e been d is c a rd e d .
A ccording t o Schanz th e e f f e c t i v e c lo s u re o f th e d u c tu s i s in flu e n c e d
by th e deg ree o f r e s p i r a t i o n .
I f th e r e s p i r a t i o n i s d e f i c i e n t th e n th e
p u l l on th e f r e e end (pulm onary) o f t h e d uctus i s weak, th e d u ctu s w i l l
o n ly narrow s l i g h t l y and th e pulm onary c i r c u l a t i o n w i l l d ev elo p p o o rly . I f
th e r e s p i r a t i o n i s s tro n g a t th e b e g in n in g th e n th e d u ctu s i s c lo s e d ; i f i t
a g a in becomes d e f e c tiv e ,th e n th e d u c tu s w i l l open a g a in and th e blo o d
-1 1 3 -
w i l l a g a in flow th ro u g h th u s o a u sin g th e pulm onary c i r c u l a t i o n t o s u f f e r .
S c h a rfe d id n o t b e lie v e t h a t th e f i l l i n g o f th e lu n g s w ith a i r had
any e f f e c t on th e change i n p o s itio n o f th e h e a r t sin c e th e flow rem ained
c o n s ta n t.
L inzenm eier c a r r ie d o u t ex p erim en ts to d eterm in e t h i s p o in t
and found t h a t a change i n p o s i t i o n r e s u lte d in each case i n w hich th e
lungs were i n f l a t e d , th e e n t i r e h e a r t was l i f t e d and r o t a t e d on i t s lo n g
a x is tow ard th e l e f t .
s tillb o rn s .
These e x p erim en ts were c a r r ie d o u t on newborns and
The p a t t e r n o f e x p an sio n i s n o t s im ila r to t h a t of a b a llo o n
a s p o in te d o u t by L inzenm eier and th e r e f o r e a d if f e r e n c e w i l l n a t u r a l l y
o c c u r.
A ddison s tu d ie d th e p a t t e r n o f e x p an sio n o f th e lu n g s and found
t h a t p a r t o f th e l i q u i d in th e u p p er p a r t o f th e r e s p i r a t o r y t r a c t i s
drawn downwards and p a r t rem ains d i s t r i b u t e d a lo n g th e w a lls o f th e a i r
p a ssa g es when th e f i r s t i n s p i r a t i o n o c c u rs .
The fluid drawn downwards i s
c a rrie d in to th e lu n g s and d i s t r i b u t e d alo n g th e w a lls o f th e a l v e o l i and
o th e r s p a c e s .
The e x p an sio n of th e lungs i s g ra d u a l s in c e th e r e s p i r a t o r y
re q u ire m e n ts o f th e newborn a r e n o t g r e a t a s shown by th e f a c t t h a t an
in f a n t can be made t o b re a th e a f t e r t e n t o f i f t e e n m in u tes o f a s p h y x ia .
(F eld m an ).
This o n s e t o f r e s p i r a t i o n has n o t only le d t o f i l l i n g and ex p an sio n
o f th e lu n g s b u t a ls o t o changes i n th e i n t r a - t h o r a c i c p re s s u re o f th e
f e tu s and newborn.
S c h u ltz e found t h a t b e fo re b re a th in g th e organs o f
th e body a re under e q u a l p r e s s u r e .
A fte r th e f i r s t i n s p i r a t i o n t h i s u n i ­
form p re s s u re i s v ery d e f i n i t e l y lo w ered .
t o r i s e somewhat.
E x p ira tio n a llo w s th e p re s s u re
Through r e s p i r a t i o n th e e n t i r e p re s s u re w ith in th e
th o ra x i s d im in ish e d and th e l a t e r a l p re s s u re d ecrea se d le a d in g t o le s s e n ­
in g o f r e s i s t a n c e and in c r e a s e i n f i l l i n g o f th e blood v e s s e ls in th e
-1 1 4 -
th e th o r a x .
The b lo o d p re s s u re f a l l s i n th e th o r a c ic b lo o d v e s s e ls b u t
t h i s i s com pensated fo r by th e in c re a s e d f i l l i n g .
Strassm ann a ls o sup­
p o rte d t h i s e x p la n a tio n o f th e e f f e c t s o f th e o n s e t of r e s p i r a t i o n .
H am ilton, Woodbury and Woods a ls o b e lie v e d t h a t th e i n t r a - t h o r a o i c
p re s su re was red u ced a t b i r t h .
E very change o f p re s s u re i n th e th o r a c ic
c a v ity was tr a n s m itte d t o th e b lo o d .
The a r t e r i o l e s and c a p i l l a r i e s o f
th e lu n g s were a f f e c t e d by th e p e r io d ic f lu c t u a t i o n s in i n t r a - t h o r a c i c
p r e s s u r e , b e in g p u lle d away from th e c o n te n ts by th e low ered i n t r a th o ra o ic p re s s u re an d th u s p e r m ittin g more blo o d t o flow th ro u g h .
The v a rio u s t h e o r i e s o f c lo s u re o f th e d u ctu s a r t e r i o s u s and i t s r e ­
s u lta n t e f f e c t s upon th e f e t a l c i r c u l a t o r y system le a d in g to th e p o s tn a t a l
type have been e x te n s iv e ly d is c u s s e d a s a b a s is f o r a th o ro u g h u n d e r­
sta n d in g o f th e o b s e rv a tio n s n o te d in th e p r e s e n t w ork.
I I I . MATERIALS AUD LETIIODS
-1 1 5 -
MTERIALS MID METHODS
The m a te r ia ls u t i l i z e d in t h i s s tu d y c o n s is t o f a s e r i e s o f one
hundred and f o r t y c ad a v e rs ra n g in g i n age from f iv e f e t a l months t o
one y e a r a f t e r b i r t h .
A nthropom etric o b s e rv a tio n s were made and th e s e
c ad a v e rs were th e n embalmed in a t e n p e rc e n t s o lu tio n o f fo r m a lin .
A
s u f f i c i e n t amount of embalming s o l u tio n was i n j e c t e d in to th e f e tu s e s
and newborns th ro u g h th e u m b ilic a l v e in t o p ro p e rly f i x and h ard en th e
m a te ria l.
P r o p o r tio n a te ly l a r g e r am ounts w ere in je c te d in to th e fem oral
a r t e r y o f th e o ld e r specim ens.
I n f a n ts h av in g a cro w n -h eel le n g th b e ­
tw een 4-5 and 50 cm ., w eighing a b o u t 3000 gms. and having a th o r a c ic
in d e x ran g in g between 86 and 100 w ere c o n sid e re d f u l l - t e r m newborns
a c c o rd in g t o th e s ta n d a rd a s fo rm u la te d by Scammon and R ucker ( 2 1 ) .
ITo specimens i n which p a th o lo g ic a l changes c o u ld be o b serv ed m aorosoop i o a l l y w ere u s e d .
The m a te r ia l was p re p a re d f o r d is s e c t i o n by im bedding each cad av er
on i t s back i n wax to a le v e l mid-way betw een th e a n t e r i o r and p o s t e r i o r
body w a l l s .
The exposed p a r ts o f th e body were a ls o c o a te d w ith wax and
th e wax removed as th e d is s e c tio n p ro g r e s s e d .
wax was tw o -fo ld i
The p u rp o se o f im bedding in
( l ) t o p re v e n t any movement and d i s t o r t i o n due to
h a n d lin g and (2) t o m inim ize changes due to d ry in g .
P in s were imbedded
in th e fo re h e a d , sh o u ld e r and sym physis p u b is , ab o u t 2 mm. o f th e p in s
rem ain in g exposed above th e s u rfa c e to serv o a s o r i e n t a t i o n p o in ts in
l i n i n g up and superim posing th e s u c c e s s iv e d raw in g s, e t c .
Since s e v e ra l
p in s had been imbedded a t v a rio u s p o in ts in th e cad av er and th e s e o r i e n t a ­
t i o n p o in ts fix e d upon th e o rth o s c o p ic draw in g , i t was e a s i l y p o s s ib le
re p e a te d ly to lin e - u p th e drawing w ith th e specim en,
These o r i e n t a t i o n
p o in ts a ls o made p o s s ib le com parison of th e p o s itio n s o f th e v a rio u s
-1 1 6 -
v is c e r a i n r e l a t i o n t o e ac h o th e r by m e re ly superim p o sin g one draw ing
upon a n o th e r , l i n i n g up th e m arking p o in ts and view ing by tr a n s m itte d
lig h t.
The d is s e c tio n s w ere made in s e v e r a l s ta g e s and re c o rd e d by means
o f p h o to g ra p h s, drawing and c a s t s .
The f i r s t s te p o f each s ta g e was to
make an o rth o so o p ic draw ing by means o f an a p p a ra tu s d e sig n e d by Scammon
and m o d ified by Noback ( ’ 2 8 ).
draw ings had been made.
Photographs were ta k e n a f t e r th e o rth o s o o p ic
A fte r drawing and p h o to g rap h in g th e d is s e c t i o n s ,
c a s ts w ere made, d i r e c t l y from th e specim en, th e v is c e r a rem ain in g u n d is ­
tu r b e d .
The m a te r ia ls u sed and th e te c h n iq u e employed in c a s tin g have
been d e sc rib e d i n d e t a i l by Rehman and Noback ( '3 7 ) .
Models o f embryos a n d young f e tu s e s made a c c o rd in g t o th e Born wax
p la te m ethod, were made by His (1 8 8 7 ), Hammer (1 8 9 3 ), M all (1 8 9 8 ), Jaokson
and B ujard ( ’ 1 4 ), and o th e r s , whioh e x h i b it th e v a rio u s s t r u c t u r e s o f th e
th o ra x and t h e i r r e l a t i o n s .
In t h i s stu d y c a s t s o f a c t u a l d i s s e c t io n s
w ere made and th e s e have been d em onstrated by Noback and Rehman ( ’ 3 5 ), (* 3 7 ) .
M easurem ents o f th e d u ctu s a r t e r i o s u s , pulm onary a r t e r y and th e a o r t a
w ere ta k e n .
H is to lo g ic a l s e c tio n s o f t h i s fo rm a lin embalmed m a te r ia l
w ere p re p a re d and s ta in e d w ith h aem ato x y lin and t r i o s i n and a l s o w ith
Van H o f f 's e l a s t i c s t a i n and t r i o s i n t o d i s ti n g u is h s t r u c t u r a l d i f f e r ­
ences betw een th e d u c tu s and th e pulm onary a r t e r y and a o r t a .
The s te p s i n th e d is s e c tio n pro ced u re w ere a s A llow s:
The e x te r n a l
form o f th e i n f a n t was photographed and drawn a s a v i s i b l e re c o rd o f
th e o o n d itio n o f th e specim en.
The s k in , p e c to r a l and i n t e r o o s t a l
-1 1 7 -
m uscles were r e f l e o t e d and th e sternum , c o s t a l c a r t i l a g e s , r i h s and
c l a v i c l e s c le a n e d as f a r p o s t e r i o r l y a s p o s s ib le #
corded by p h o to g ra p h s, draw ings an d c a s t s .
T his s ta g e was r e ­
The m uscles o f th e neok
a tta o h in g t o th e manubrium s t e r n i and c l a v i c l e were d e tac h e d n e x t and
r e f l e c t e d upward t o expose th e c e r v ic a l p o r tio n of th e thymus and th y r o id
g la n d s , th e c a r o tid v e s s e l s , v a g i and r e c u r r e n t la ry n g e a l nerves^ and th e
tr a c h e a .
The s u p e r io r e x te n t o f th e thymus and i t s r e l a t i o n to th e
th y r o id g lan d were th u s c l e a r l y shown.
The a n t e r i o r and l a t e r a l p o rtio n s
of th e th o r a c ic cage were n e x t removed and th e r e f l e c t i o n s o f th e p le u ra
observed and re c o rd e d .
In th e fo llo w in g s ta g e th e p le u ra and a r e o l a r
t i s s u e w ere removed, th e thymus c lea n e d and th e re g io n th e n drawn, ph o to ­
graphed and c a s t#
S e v e ra l d is s e c t i o n p ro c e d u res were employed f o r th e su b seq u en t s te p s
to o b ta in a com prehensive u n d e rs ta n d in g o f th e re g io n involved#
Ono d i s ­
s e c tio n p ro ced u re c o n s is te d o f rem oving th e lungs by c u ttin g th ro u g h t h e i r
r o o t s , th e thymus and p e ric a rd iu m rem ain in g i n s 1tu in o rd e r t o d eterm in e
th e r e l a t i o n s o f th e thymus t o th e pulmonary a r t e r y and d u ctu s a r te r io s u s #
D raw ings, photographs and c a s t s were a ls o 2nade o f t h i s s ta g e o f th e d i s ­
s e c tio n .
The thymus and th e p e ric a rd iu m -were th e n removed and th e h e a r t ,
g r e a t v e s s e ls and ductus
c le a n e d , drawn, photographed and
c a s t#
A nother d i s s e c t i o n , t o o b ta in th e thym ic bed and i t s e x te n t l a t e r a l l y
and p o s t e r i o r l y , c o n s is te d o f removing th e thym us, th e lungs rem ain in g
in s itu .
T his s ta g e was re c o rd e d by p h o to g ra p h s, draw ings and c a s t s
and
th e thymus was then replaced t o make a d d itio n a l o b s e rv a tio n s #
A l a t e r a l ap p ro ach t o th e d u ctu s from th e l e f t in v o lv e d rem oving
th e l e f t arm , sh o u ld er and s u p e r f i c i a l m u scu latu re o f th e n eck , th o r a x , and
-1 1 8 -
back to expose th e r ib s w hich were th e n draw n, photographed and c a s t .
The upper seven r i b s were th e n d i s a r t i c u l a t e d a t t h e i r s t e r n a l and
v e r te b r a l a tta c h m e n ts and th e u p p er lo b e o f th e l e f t lung removed; th e
l e f t bronchus re m a in in g i n t a c t t o r e t a i n i t s r e l a t i o n t o th e d u c tu s .
The p o s t e r i o r and l a t e r a l e x te n t of th e thymus and p eric ard iu m upon th e
duotus was th e n d e te rm in e d .
The m e d ia s tin a l p le u ra and p eric ard iu m were
th e n removed t o s tu d y in more d e t a i l th e to p o g rap h y of th e d u c tu s.
The
v e r te b r a l l e v e l o f th e ductus was e a s i l y o b ta in e d a t t h i s sta g e by ’m eans
of th e o u t ends o f th e d i s a r t i c u l a t e d r i b s .
The v e r te b r a l column was th e n
s a g i t t a l l y s e c tio n e d in an a n t e r o - p o s t e r i o r p lan e and th e lo v e ls o f th e
v a rio u s s t r u c tu r e s d e term in e d .
The l a t e r a l d is s e c tio n was a ls o combined
w ith th e a n t e r i o r d is s e c tio n s by e x te n d in g th e removal o f th e r i b s to th e
v e r te b r a l column p o s t e r i o r l y .
A s im ila r d is s e c tio n procedure was fo llo w ed
in th e p o s t e r i o r d i s s e c t i o n .
The v e r t e b r a l column, scap u lae and r i b s were
removed and th e s t r u c t u r e s s tu d ie d and re c o rd e d a s in th e above d is s e c t io n s .
Two s e r i e s o f m easurem ents were made; one s e r ie s to o b ta in th e e x ­
t e r n a l m easurem ents p r i o r to embalming and a n o th e r s e r ie s of th e d u c tu s,
a o r ta and pulm onary tru n k and b ra n c h e s , a f t e r th e d is s e c tio n had p ro g re sse d
s u ffic ie n tly .
A d e s c r ip tio n o f th e e x te r n a l m easurem ents made p r i o r to
embalming i s a s fo llo w s :
Craw n-heel - from th e v e rte x o f th e crown to th e h e e l.
C ircum ference a t n ip p le s - tr a n s v e r s e c irc u m fe re n ce a t th e n ip p le s .
C ircum ference a t x ip h o id sternum - c irc u m fe re n ce a t le v e l o f x ip h i­
s t e r n a l ju n c tio n a s in d ic a te d by th e s t e r n a l n o tc h .
C ircum ference a t 1 0 th r i b - tr a n s v e r s e plane o f tru n k a t le v e l o f
10t h r i b .
-1 1 9 -
G re a to s t tr a n s v e r s e n i p p le s - g r e a t e s t t r a n s v e r s e d ia m e te r of t h e c h e s t
i n th e h o r i z o n t a l plane a t th e l e v e l of th e n i p p l e s .
G r e a te s t tr a n s v e r s e x ip h o id sternum - g r e a t e s t b r e a d th o f th e tr u n k i n
th e t r a n s v e r s e plane a t t h e l e v e l of th e x i p h i - s t e r n a l ju n c t i o n .
G r e a te s t tr a n s v e r s e 1 0 th r i b - g r e s t e s t b r e a d th of t h e tr u n k i n th e
t r a n s v e r s e plane a t t h e l e v e l of th e 10 th r i b .
A n te r io r p o s t e r i o r n i p p l e s - g r e a t e s t d ia m e ter in t h e h o r i z o n t a l p la n e
and th e median l i n e , betw een t h e a n t e r i o r and p o s t e r i o r s u r f a c e s of
th e c h est.
A n te r io r p o s t e r i o r x ip h o id sternum - g r e a t e s t d is ta n c e between th e a n t e r i o r
and p o s t e r i o r s u rfa c e s o f th e ch o st i n th e m id lin e a t the l e v e l of th e
x ip h i-s to rn a l ju n c tio n .
In a d d i t i o n to t h e above m easurements, a n o th e r s e r i o s was ta k e n of the
ductus a r t e r i o s u s , pulmonary a r t e r y , anu a o r t a when t h e a p p r o p r ia te s ta g e s
of th e d i s s e c t i o n s were re a c h e d .
A d ia g r a r .a tic s k e tc h showing th e lo c a t i o n s
of th e v a rio u s measurements i s shown i n F i g . 32.
The numbers shown on th e
diagram r e p r e s e n t th e l o c a t i o n anu a r e a in c lu d e d i n each measurement.
In o m .
L .C om C aR otU
-12 0 -
The fo llo w in g i s a d e t a i l e d d e s c r i p t i o n o f th e s e m easurem ents.
The numbers p la c e d b e fo re th e d e s c r i p t i o n s of e ach measurement c o r r e s ­
pond t o th o s e o f th e t a b l e s of d a t a .
1 . S u p e rio r le n g th of ductus a r t e r i o s u s - th e measurement i s made
a lo n g th e s u p e r io r s u r f a c e of th e ductus a r t e r i o s u s from a p o in t
d i s t a l t o th e b i f u r c a t i o n o f t h e pulmonary a r t e r y , t o tho s u p e r i o r
a n g le formed by th e union o f th e ductus and th e descend in g a o r t a .
2 . I n f e r i o r le n g th of ductus - from l a t e r a l a ng le formed by l e f t p u l ­
monary a r t e r y end ductus t o v e r te x of i n f e r i o r o b liq u e a t j u n c t i o n
o f ductus and descending a o r t a ,
3 . D ista n c e between r o o t o f s u b c la v ia n a r t e r y and o r i f i c e o f ductus from i n f e r o - l a t e r a l angle formed by s u b c la v ia n a r t e r y and a r c h o f
th o a o r t a t o t h e s u p e r io r a n gle between th e ductus and a o r t a .
4 . C re s c e n tic space between th e ductus and th e a rc h of a o r t a - from
i n f e r i o r and a n t e r i o r b o rd e r o f a o r t a t o s u p e r io r and p o s t e r i o r
b o rd e r of du ctu s a r t e r i o s u s - o p p o s ite tho r o o t of t h e l e f t common
c aro tid a rte ry .
5 . D iameter of
e n tra n c e o f
d i s t a l p a r t of descending a o r t a -
d ia m e ter d i s t a l t o
ductu s i n t o descending a o r t a .
G, Diameter of proxim al p a r t of descending a o r t a - d ia m e te r o f d e s ­
cending a o r t a proxim al t o th e un io n of du ctu s and a o r t a .
7. Diameter o f a o r t i c a rc h i n th e f r o n t a l p la n e - d ia m e te r between th e
innom inate and l e f t common c a r o t i d a r t e r i e s measured s u p e r o - i n f e r i o r l y .
C.
Diameter of
a o r t i c a r c h i n a h o r i z o n t a l p la n e
- tho a n t e r o - p o s t e r i o r
d ia m e ter of
a o r t i c a rc h between th e innom inate and l e f t common c a r o t i d
a rte rie s.
S. Diameter of d i s t a l aid o fd u c tu s a r t e r i o s u s - d ia m e te r o f d u ctu s im­
-1 2 1 -
m e d ia te ly proxim al t o e n tra n c e i n t o a o rta *
10* D iam eter o f th e m id d le d uctu s a r t e r i o s u s - d ia m e te r midway betw een
b i f u r c a t i o n o f pulmonary a r t e r y and d escen d in g a o r t a .
1 1 . D iam eter o f d u o tu s a r t e r i o s u s a t p ro x im al end - d ia m e te r o f d u ctu s
a t p o in t o f o r ig i n j u s t d i s t a l t o b i f u r c a t i o n o f pulm onary a r te r y *
1 2 . D iam eter o f pulm onary a r t e r y - d ia m e te r o f m ain pulm onary a r t e r y
proxim al t o b if u r c a tio n *
1 3 . D iam eter o f l e f t pulm onary a r t e r y i n f r o n t a l p lan e*
14. D iam eter o f l e f t pulm onary a r t e r y in a n t e r o - p o s t e r i o r p la n e .
1 5 . The s u p e r io r and i n f e r i o r le n g th s o f th e d u c tu s were m easured and
th e a v erag e o f th e two m easurem ents was ta k e n a s th e t r u e l e n g th .
The above l i s t e d m easurem ents though n o t in c lu d e d i n t h i s t h e s i s a r e
a v a il a b le i n t h i s la b o r a to r y .
In a la rg e number o f in f a n t s a c r e s c e n t io
space was found betw een th e a o r ta and d u ctu s a r t e r i o s u s .
T h is space was
c l e a r l y d is c e r n ib l e when th e d e n se r c o n n e c tiv e and th e a r e o l a r t i s s u e
w ere c le a n e d away*
DDbGhiPTiu:;
a i :d d i s c i s s i o n
-1 2 2 -
DSSCRIPTIOII AITD DISCUSSION
In t h e fo llo w in g d e s c r i p t i o n and d is c u s s io n of the anatomy of th e
re g io n th e p re v io u s resume o f t h e s ta g e s of t h e d i s s e c t i o n w i l l be d i s ­
cu sse d i n g r e a t e r d e t a i l .
The m o rp h o lo g ica l and h i s t o l o g i c a l s t r u c t u r e
o f t h e d u ctus w i l l be a n a ly z e d t o determ ine i f p o s s i b l e th e r o l e tnlcen
by each component i n b rin g in g ab o u t c lo s u r e o f t h e d u c tu s .
The s k i n , subcutaneous t i s s u e and t h o r a c i c m u scu latu re were removed
and t h e t h o r a c i c cage c o n s i s t i n g of t h e sternum , r i b s and c l a v i c l e s t u d i e d .
The p o s i t i o n of th e manubrium s t e r n i a s observed i n t h i s s tu d y c o rrespo nd ed
to t h a t d eterm ined by Dwight and n o tc h (lG S l) who found i t t o be h ig h e r in
th e newborn t h a n in * tho a d u l t ; a d e sc e n t o c c u rrin g u n t i l th e a d u l t le v o l
i s re a c h e d .
This d e sc e n t nay bo due t o an i n c r e a s e in tho s iz e of th e
th o r a x and a l s o t o o s s i f i c a t i o n of th e c a r t i l a g i n o u s sternu m .
The s u p e r io r
b o rd e r of th e sternum i s a t th e l e v e l of th o f i r s t t h o r a c i c v e r t e b r a .
The
r i b s a r e more n e a rly h o r i z o n t a l and t h e r e f o r e th e a n t e r o - p o s t e r i o r d ia m e ter
is g r e a t e r t h a n i n l a t e r l i f e .
The d i r e c t i o n o f th e f i r s t r i b i s s u p e r i o r ,
l a t e r a l and p o s t e r i o r ; tho l a t e r a l t h r e e - f o u r t h s ly in g b e n e a th th e c l a v i c l e .
Tho i n t e r c o s t a l space betw een th e f i r s t and second r i b s i s g r e a t e r on th e
l e f t th a n on th e r i g h t ; t h e r i b s on t h e l e f t t h e r e f o r e a t t a c h t o th e sternum
a t a s l i g h t l y lower l e v e l tjian th e c a r t i l a g e s of th e r i g h t r i b s .
The a n t e r i o r m u s c u la tu re o f th e neck m s removed to expose th o c e r v i c a l
p o r t i o n of t h e thymus and t h y r o i d g la n d s .
The e x te n t of th e c e r v i c a l p o r t i o n
o f t h e thymus above t h e upper b o rd e r o f th e manubrium s t e r n i m s th u s e a s i l y
d e te rm in e d .
The c e r v i c a l p o r t i o n of t h e thymus i s covered by^ th e a n t e r i o r
c e r v i c a l m uscles a t t a c h i n g t o th e manubrium.
The thymus i s e n c lo s e d i n a
t h i c k c o n n e c tiv e t i s s u e c ap su le t h a t i s th ic k e n e d i n th e c e r v i c a l p o r t i o n .
F ib ro u s c o n n e c tiv e t i s s u e s tr a n d s extend from th e upper pole of th e thymus
-1 2 3 -
F i g . 33.
u r th o d ia g ra p h ic composite
drawing t o show l e v e l s , e t c . ,
(Newborn) •
F ig . 34.
A n t e r i o r th o r a c ic and c e r v i c a l
m u scu latu re removed t o show
c e r v i c a l e x te n t of thymus and
t h y r o i d g la n d . (Newborn)
t o th e i n f o r o - l a t e r a l s u r f a c e of t h e t h y r o i d g la n d .
These s tr a n d s ap p ea r
more f r e q u e n t l y on th e r i g h t th a n l e f t and a re o c c a s io n a ll y a t t a c h e d t o
th e c a r o t i d s h e a th p o s t e r i o r l y .
These s tr a n d s of co n n ec tiv e t i s s u e because
o f t h e i r p o s i t i o n p ro b a b ly f u n c t i o n as su p p o rtin g ligam ents f o r tho thym us.
The c e r v i c a l p o r t i o n o f th e thymus, w hich p r o j e c t s 1 .5 cm. i n t o th e
neck i n th e newborn p r e s s e s a g a i n s t t h e sternum i n f e r i o r l y and p o s t e r i o r l y
a g a i n s t t h e innom inate v e in and a r t e r y , s u p e r io r vena cav a, a o r t a , t r a c h e a
and eso ph agu s.
The f l a t t e n e d appearance of th e s e s t r u c t u r e s upon p o s t ­
mortem ex am in atio n e x h i b i t d e f i n i t e evidence o f t h i s co m p ressio n.
The a n t e r i o r p a r t o f th o t h o r a c i c cage was removed and th e p l e u r a l
r e f l e c t i o n s and thymus s tu d ie d i n more d e t a i l .
The changes i n shape and
topography o f t h e thymus th ro u g h o u t f e t a l l i f e were found t o be i n agreem ent
-1 2 4 -
F ig . 3 5 ,
L e f t l a t e r a l view.
Body w a ll, up p er lobe of
l e f t lung and thymus removed
to expose d u c tu s . (Newborn)
w ith th e o b s e rv a tio n s re c o rd e d by Koback (* 2 3 ).
The thymus i s p a r t i a l l y co v ered by p le u ra and r e s t s upon th e upper
p a r t o f th e p e r i c a r d i a l s a c .
The shape o f th e thym us, e x te n t o f p le u r a l
r e f l e c t i o n s and degree o f e x p an sio n o f th e lu n g s and t h e i r changes th ro u g h ­
o u t f e t a l l i f e have a ls o been s tu d ie d and re c o rd e d by Koback ( '2 1 ) , (* 2 3 ).
The thymus i s long and narrow d u rin g e a r ly f e t a l l i f e and th e n becomes
b ro a d e r tow ard th e l a t t e r p a r t o f f e t a l l i f e when th e th o ra x in c re a s e s in
l a t e r a l d ia m e te r.
The thymus rem ain s broad in th e newborn, b u t a s th e
lungs expand w ith o n se t o f r e s p i r a t i o n
it.
becomes e lo n g a te d , ap p ro ach in g
-1 2 5 -
a g a in th e e a r l i e r f e t a l ty p e .
The th o r a c ic p o r tio n o f th e thymus i s co v ered i n f e r i o r l y and l a t e r a l l y
by p le u r a , a c e n tr a l m edian space rem aining uncovered and v a ry in g in w id th
between 12 mm* s u p e r io r ly a t th e ju g u la r n o tc h o f th e stern u m to a b o u t 4 mm.
a t th e i n f e r i o r b o rd e r o f th e thym us.
T his uncovered a re a i s due t o th e
f a i l u r e , a s y e t , o f th e p le u r a l r e f l e c t i o n s to m eet m e d ia lly a s in th e
a d u lt, Hoback ( ’2 1 ), (* 2 5 ), d ra p e r ( ’ 2 1 ).
When tr a c e d i n f e r i o r l y , th e
p le u r a l m argins a r e s e p a ra te d by a d is ta n c e o f 8 to 20 mm.
T his i s a t
v a ria n c e w ith th e f in d in g s o f T anja (1891) who s t a t e s t h a t th e m e d ial
m argins o f th e p le u r a l sa c s u s u a lly m eet b eh in d and to th<5 l e f t of th e
m id lin e of th e sternum and t h a t t h i s a p p ro x im a tio n e x te n d s b ehind th e en ­
t i r e le n g th of th e stern u m .
The p le u ra rem ains w id e ly s e p a ra te d d u rin g
f e t a l l i f e and undergoes c lo s e r a p p ro x im a tio n a f t e r b i r t h when th e lungs
expand and move m e d ia lly '.
In s e v e r a l o f th e o ld e r in f a n t s s tu d ie d , th e
p le u ra o f both s id e s d id m eet f o r th r e e - f o u r t h s o f th e d is ta n c e above th e
diaphragm , th e upper o n e -fo u rth re m a in in g s e p a r a te d .
The r e f l e c t i o n o f th e
p le u ra from th e l a t e r a l and i n f e r i o r s u rfa c e o f th e p e ric a rd iu m i s c o n tin u e d
p o s t e r i o r l y to th e r o o t o f th e lu n g .
The l a t e r a l r e f l e c t i o n o c cu rs a t th e
sev e n th r i b on th e r i g h t and s l i g h t l y h ig h e r on th e l e f t and e x ten d s t o th e
diaphragm .
I t is th e n r e f l e c t e d from th e m id lin e a t th e le v e l o f th e s ix t h
r i b and c o n tin u e s o b liq u e ly ' downward and l a t e r a l l y c ro s s in g th e s i x t h i n t e r ­
c o s t a l space and sev e n th r i b .
The p l e u r a l r e f l e c t i o n s extend to th o tw e lf th
r i b p o s t e r o - l a t e r a l l y form ing deep c o sto p h re n ic s in u s e s i n to w hich th e i n ­
f e r i o r p a r t s o f th e lu n g s do n o t e x te n d .
As th e p le u ra i s tr a c e d m e d ia lly
in th e l e f t p le u r a l c a v ity i t c o v ers th e sy m p ath etic tr u n k , th e d escen d in g
a o r ta and i t s b ra n c h es and i s th e n r e f l e c t e d on to th e l a t e r a l s u rfa c e o f
th e low er p a r t of th e esophagus and p o s te r io r s u rfa c e o f th e r o o t o f th e
-1 2 6 -
l e f t lu n g .
Above th e r o o t of th e l e f t lu n g th e p le u ra c o v e rs th e a rc h ,
d escending a o r t a and d u c tu s a r t e r i o s u s .
The vagus and r e c u r r e n t la ry n g e a l
n e rv e s a re f ir m ly fix e d t o th e w a ll o f th e d u c tu s by t h i s p l e u r a l r e f l e c t i o n .
As th e p le u r a p a ss e s from th e l a t e r a l s u rfa c e o f th e d escen d in g a o r ta to
th e d u c tu s i t c o v ers th e s u lc u s form ed by th e ju n c tio n o f th e d u ctu s and
a o rta .
The vagus n e rv e c ro s s e s th e l a t e r a l s u rfa c e o f th e d u c tu s im m ediately
above (p ro x im al t o ) t h i s groove o r s u lc u s w hich i s f i l l e d w ith f a t and lo o se
c o n n e c tiv e t i s s u e .
The p le u ra c o v e rs th e d u c tu s to th e l a t e r a l s u rfa c e o f
th e deep p o r tio n o f th e thymus \vhicli l i e s on th e ductus and the pleura is then ocntin u o u s m e d ia lly and a n t e r i o r l y .
*
The changes in shape and to p o g ra p h y of th e thymus have been d is c u s s e d
p r e v io u s ly .
I t s to p o g rap h y in th e l a t e f e tu s and newborn w i l l now be d e s ­
c rib e d in d e t a i l .
A n te r io r ly th e thymus i s lim it e d by th e sternum and r i b s
in tl:ie th o ra x and in th e neck by th e a n t e r i o r group o f c e r v ic a l m uscles
a tta c h in g to th e manubrium s t e r n i .
P o s t e r i o r l y th e thymus r e s t s a g a in s t
th e p e ric a rd iu m and r o o ts o f th e g ro a t v e s s e l s .
The l e f t innom inate v e in
grooves th e p o s te r io r s u rfa c e of th e thymus v e ry d e e p ly .
F re q u e n tly th e
thymus c o m p le te ly e n c lo s e s th e v e in and ex ten d s p o s t e r i o r l y to th e innom inate
a r t e r y and t r a c h e a .
In th e th o ra x th e thymus e x ten d s l a t e r a l l y and p o s te r io r ­
l y betw een th e m e d ia l su rfa o e of th e l e f t lu n g and th e pulm onary a r t e r y ,
d u ctu s a r t e r i o s u s and p e ric a rd iu m .
The thymus o v e rla p s th e pulm onary tru n k
and th e b e g in n in g o f th e d u c tu s i n th e f e t u s .
The thymus w i l l th e r e f o r e te n d
to f i l l th e a v a il a b le f r e e space and become molded by th e su rro u n d in g
s tru c tu re s .
W ith th e o n s e t o f r e s p i r a t i o n th e lu n g s expand and m ig ra te
m e d ia lly r e s u l t i n g i n a d e c re a se i n a v a il a b le f r e e space f o r th e thym us.
in c re a s e d " c o m p e titio n f o r space" among th e th o r a c ic v is c e r a o c c u r s .
The
An
-1 2 7 -
Fig* 36. P o s t e r o - l a t e r a l v iew . Thymus
e n c lo s in g l e f t innom inate v e in l i f t e d
away from d u c tu s , (Newborn)
F ig , 3 7 . Diagram showing
s t r u c t u r e s in r e l a t i o n to
p o s t e r i o r s u rfa c e o f th e
thym us• ( Newborn)
r i b s and sternum have l i f t e d w ith th e o n s e t o f r e s p i r a t i o n b u t t h i s ex ­
p a n sio n o f th e th o ra x is n o t s u f f i c i e n t t o accommodate th e changed s p a t i a l
r e l a t i o n s o f th e th o r a c ic v i s c e r a .
The h e a r t which is r e l a t i v e l y s o lid and
h e l d i n p o s itio n by th e p e ric a rd iu m and r o o ts o f th e g r e a t v e s s e ls i s r o ­
t a t e d s l i g h t l y a n t e r i o r l y , i n f e r i o r l y and m e d ia lly .
The lu n g s , w hich have
f i l l e d th e p o s te r io r p o r tio n o f th e p l e u r a l c a v i t i e s p re v io u s to r e s p i r a t i o n ,
expand and in c re a s e i n e x te n t m e d ia lly and a n t e r i o r l y to th e thymus so as
a lm o st e n t i r e l y to f i l l th e p l e u r a l c a v i t i e s .
Some s tr u c tu r e s th e r e f o r e
g iv e way to make room f o r t h i s demand f o r more space by th e lu n g s .
The
thymus a s w e ll a s th e m e d ia l s u rfa c e o f th e lu n g s , a o r t i c a r c h , innom inate
a r t e r y , tr a c h e a , esophagus and d u ctu s a r t e r i o s u s show e v id en c e s o f m olding
by p re s s u re e x e r te d upon them .
The thymus and d u ctu s a re a f f e c t e d m ost by
-1 2 8 -
t h i s c o m p e titio n f o r sp a c e .
The d u c tu s i s com pressed l a t e r a l l y by th e
lu n g s so t h a t i t s l a t e r a l e x te n t i s d e c re a s e d .
The thymus becomes e lo n ­
g a te d an d fo rc e d s u p e r io r ly in to th e neck and p o s t e r i o r l y a g a in s t th e
g re a t v e s s e ls .
The thymus a l s o com presses th e d u ctu s a r t e r i o s u s m e d ia lly
and i n f e r i o r l y and p re s s e s a g a in s t th e lu n g s l a t e r a l l y .
As a r e s u l t o f
t h i s c o m p e titio n f o r space th e thymus i s e lo n g a te d and i t s a n t e r o - p o s t e r i o r
d ia m e te r in c re a s e d so t h a t p re s s u re i s b ro u g h t t o b e a r upon th e pulmonary
h a l f o f th e d u c tu s by th e thymus an d on th e d i s t a l h a l f ( a o r t i c ) o f th e d u ctu s
by th e m edial s u rfa c e o f th e l e f t lu n g .
The a n t e r i o r b o rd e r o f th e l e f t lung is s i t u a t e d a t a g r e a t e r d is ta n c e
from th e m id lin e th a n th e r i g h t lu n g and i s v e ry deeply n o tc h ed i n i t s m id­
d le h a l f so t h a t a la rg e a re a c o n s is tin g o f th e l e f t s u r f a c e , apex and l e f t
v e n t r i c l e o f th e h e a r t rem ains uncovered by t h i s lu n g .
The m e d ia s tin a l
s u rfa c e o f th e r i g h t lung i s in c o n ta c t w ith th e r i g h t in n o m in ate v e in and
s u p e r io r vena cava p o s t e r i o r l y and th e r i g h t l a t e r a l s u rfa c e o f th e thymus
a n t e r i o r l y , b u t n o t w ith th e a o r t a .
The l e f t lu n g i s s m a lle r and e x ten d s
f u r t h e r p o s t e r i o r l y b eh in d th e h e a r t th a n does th e r i g h t lu n g .
The v e r t e b r a l
m argin o f th e l e f t lung e x ten d s m e d ia lly b eh in d th e d i s t a l p a r t o f th e a rc h
o f th e a o r ta and upper p a r t o f th e d escen d in g a o r t a and i s d e e p ly grooved
by them .
A rid g e w hich i6 found p o s t e r i o r l y on th e m e d ia s tin a l s u rfa c e o f
th e upper lo b e o f th e l e f t lung f i t s i n t o th e groove o r s u lc u s formed by
th e o v e rla p p in g of th e d u c tu s onto th e a o r ta a t th e p la c e o f e n tra n c e o f
th e d uctus in to th e descending a o r t a .
The s u lc u s h as been found in a l l
o f th e specim ens s tu d ie d and a p p e a rs to be more pronounced i n th e i n f a n t s
t h a t have b re a th e d .
F aber has d e sc rib e d such a groove o r s u lc u s , b u t has s t a t e d t h a t th e
vagus n e rv e occupied t h i s groove a s i t p a sse d o v er th e d u c tu s i n i t s c o u rse
in fe rio r ly .
The o b s e rv a tio n s o f t h i s s tu d y do n o t su p p o rt th e above fin d in g s
-1 2 9 -
S « k c f « .v iA T i /$ ,
Fig* 38. L e f t l a t e r a l view showing a rc h in g
o f th e d u ctu s and o b liq u e e n tra n c e o f d u o tu s
in to a o r t a . Thymus has been p a r t i a l l y l i f t ­
ed t o show e n t i r e e x te n t o f d u c tu s . (Newborn)
f o r th e vagus n erv e p a sse s over th e d u ctu s m e d ia l t o th e groove w hich i s
a c t u a l l y formed by th e ju n c tio n o f th e d u ctu s and d escen d in g a o r t a . (Tig. 3 9 ) .
W ith th e o n s e t o f r e s p i r a t i o n ex p an sio n o f th e u p p er lo b e o f th e l e f t
lu n g c au ses t h i s m e d ia l, p o s te r io r rid g e o r p ro tu b e ra n o e o f th e lu n g t o e x ­
pand f u r t h e r m ed ially *
T h is p ro b a b ly b rin g s a b o u t th e s h i f t i n g a n t e r i o r l y
and m e d ia lly o f th e d i s t a l p a r t of th e a rc h and d escen d in g a o r t a c a u sin g
th e d u ctu s t o f o ld over l a t e r a l l y a t i t s e n tra n c e i n to th e a o r t a .
W ith
c o n tin u e d e x p an sio n o f th e lungs t h i s l a t e r a l groove betw een th e d u ctu s
and d escen ding a o r ta i s a c c e n tu a te d and p ro b a b ly a i d s in f u r t h e r
c lo s in g th e a o r t i c e n tra n c e o f th e d u c tu s in to th e a o rta *
The m edia­
s t i n a l s u rfa c e o f th e l e f t lung i s c ro s s e d by th e p h re n ic n e rv e and
-1 3 0 -
F ig . 39. L e ft p o s te r io r v ie w , Note
p o s itio n o f l e f t vagus n erv e in r e l a t i o n
t o groove formed by e n tra n c e o f d uotus
in to a o r t a . F la tte n in g o f a o r t i c a ro h
may a ls o be se e n . (Newborn)
a ls o b e a rs a deep im p ressio n caused by r e s is ta n c e o f th e thymus w hich
r e s t s on th e r o o ts o f th e g r e a t vessel^; th e a rc h o f th e a o r t a , and th e
p o r tio n of th e d u c tu s a r t e r i o s u s im m ediately d i s t a l t o th e b i f u r c a t i o n
o f th e pulmonary a r t e r y .
In many specim ens, th e thymus sends a p ro c e ss p o s t e r i o r l y betw een th e
s u p e r io r vena c av a , l e f t innom inate v e in , and a scen d in g a o r t a .
P o s t e r i o r l y th e a o r ta r e s t s a g a in s t th e tr a c h e a and b ran ch es o f th e
vagus n e r v e .
The a n t e r i o r p a r t o f th e a sc e n d in g a o r ta i s p a r t i a l l y co v ered
by th e thymus on th e l e f t , and a n t e r i o r l y by th e m ain stem of th e pulm onary
a r t e r y , th e thymus b e a rin g a co rre sp o n d in g d e p r e s s io n .
The e n t i r e l e f t
F i g . 4 0. upper lobe o f l e f t lung
p u lle d i n f e r i o r l y t o b e t t o r expose
d u c tu s and a d ja c e n t s t r u c t u r e s . (Newborn)
F ig . 4 1 . L e f t l a t e r a l v iew ,
upper lobe o f l o f t lung removed
to show d u ctu s a rc h in g over
l e f t b ro n ch u s,(N ew b o rn )
F ig . 4 2 , Upper lo b e o f l e f t lu n g
removed t o show p o s t e r i o r e x te n t
of thymus ix ^ u o "d u ctu s and e n c lo s in g
l e f t innom inate v e in . (Newborn)
-1 3 2 -
a s p e c t o f th o a sc e n d in g a o r ta i s th e r e f o r e in c o n ta c t w ith th e r o o t
th e pulm onary a r t e r y .
of
The p e ric a rd iu m c o v e rin g th e r o o ts o f th e g r e a t
v e s s e ls i s r e f l e c t e d from th e a sc e n d in g a o r ta im m ed iately pro x im al to
th e p o in t o f o r ig in o f th e innom inate a r t e r y on th e r i g h t .
The a rc h o f
th e a o r t a ispertiaUy covered by th o p e ric a rd iu m w hich s e p a ra te s i t from th e
su rro u n d in g s t r u c t u r e s .
The innom inate a r t e r y a r i s e s from th e a rc h o f th o a o r ta to th e l e f t
o f i t s ju n c tio n w ith th e a sc e n d in g a o r t a .
T h is v e s s e l a r i s e s f u r t h e r to
th e l e f t of th e tr a c h e a i n th e i n f a n t th a n i n th e a d u l t , (Noback ( '2 1 ) ,
F ig . 4 3 . A n te r io r view o f innom inate
a r t e r y a s i t p a ss e s from l e f t to r i g h t
over th e tr a c h e a . (Newborn)
I t c o u rs e s s u p e r io r ly and l a t e r a l l y to th e r i g h t over th e a n t e r i o r s u rfa c e
o f th e tr a c h e a w hich i t com presses and is covered a t i t s p o in t o f o r ig in
by th e l o f t innom inate v e in .
The tr a c h e a alw ays shows an o b liq u e furrow
m arking th e c o u rse o f th e innom inate a r t e r y .
The t h o r a c ic p o r tio n o f th e
thymus p re s s e s agpinsttho l e f t innom inate v e in and p o s t e r i o r l y a g a in s t th e
innom inate a r t e r y cau sin g th e l a t t e r t o become f l a t t e n e d a n t e r o - p o s t e r i o r l y
-1 3 3 -
where i t c ro s s e s th e t r a c h e a .
The p re s s u re of th e thymus -was g r e a t enough
in some in f a n ts t o cau se a marked f l a t t e n i n g and s h i f t i n g o f th e innom inate
a r t e r y , and th e esophagus t o th e l e f t , th e tr a c h e a b e in g d is p la c e d t o th e
rig h t.
The a rc h o f th e a o r t a a t th e o r ig in o f th e innom inate a r t e r y ru n s
o b liq u e ly l a t e r a l l y and p o s t e r i o r l y .
In th e newborn th e d i r e c t i o n and
c o u rse o f th e a rc h o f th e a o r ta i s a lm o st d i r e c t l y a n t e r o - p o s te r io r and
o nly s l i g h t l y t o th e l e f t , and changes o n ly w ith in c re a s e in a g e , becoming
more o b liq u e l a t e r a l l y .
The a n g le made by th e a rc h o f th e a o r t a w ith th e
f r o n t a l p la n e in i t s c o u rse l a t e r a l l y and p o s t e r i o r l y i s a b o u t e ig h ty d e­
g re e s i n th e newborn and changes t o f i f t y d e g re es i n th e one y e a r o ld c h i l d .
The vagus and r e c u r r e n t la r y n g e a l n e rv e s p ass a c r o s s th e a ro h o f th e
a o r ta where i t becomes c o n tin u o u s w ith th e descending a o r t a .
The l e f t
vagus n e rv e c ro s s e s th e d uctus a r t e r i o s u s n e a r i t s e n tra n c e in to th e d e s ­
cending a o r ta and c o n tin u e s i n f e r i o r l y on i t s a n t e r i o r a s p e c t .
The r e ­
c u r r e n t laryngedL n e rv e c ro s s e s th e a rc h of th e a o r ta p ro x im al to th e v ag u s,
i . e . , c l o s e r to th e m id lin e and o r ig i n o f th e g r e a t v e s s e ls from th e h e a r t .
The r e c u r r e n t la ry n g e a l n erv e c ro s s e s th e dtictus a lm o st midway betw een
i t s o r ig i n and i t s te r m in a tio n .
T h is n erv e th e n hooks around th e d u ctu s
in a la te r o - m e d ia l d i r e c t i o n and p ro ceed s s u p e r io r ly , to th e la ry n x ,
m ed ial t o th e d u c tu s a r t e r i o s u s and a rc h o f th e a o r ta on i t s way t o th e
la ry n x .
The f i r s t p a r t o f th e r e c u r r e n t la ry n g e a l n erv e i s th e r e f o r e in
r e l a t i o n t o th e a o r ta and d u c tu s m e d ia lly and th e l e f t bronchus and l e f t
pulm onary a r t e r y i n f e r i o r l y .
The l e f t bronchus p a sse s m e d ia lly around
th e d u c tu s a r t e r i o s u s and p ro c e ed s s u p e r io r ly , th e d u ctu s a r t e r i o s u s and
a rc h o f th e a o r ta form ing i t s l a t e r a l r e l a t i o n s .
-1 3 4 -
The a rc h of th e a o r ta i s s i t u a t e d a n t e r i o r to th e tr a c h e a , esophagus
and r e c u r r e n t la ry n g e a l nerve,.
A n t e r io r ly , th e a o r t i c a rc h i s s e p a ra te d
by p e ric a rd iu m from th e thym us, th e thymus e x ten d in g p o s t e r i o r l y and
l a t e r a l l y t o th e l e f t of th e a rc h a s f a r a s th e o r ig i n o f th e s u b c la v ia n
a rte ry .
The m e d ia l s u rfa c e o f th e l e f t lobe o f th e thymus th e r e f o r e
p re s s e s a g a in s t th e a o r t i c a rc h on th e l e f t , r e s u l t i n g in a f l a t t e n i n g
o f th e a r c h .
The l e f t lung i s in r e l a t i o n to th e rem ain d er o f th o a rc h
and th e d escen d in g a o r t a .
The b i f u r c a t i o n of th e tr a c h e a o ccu rs behind
th e a rc h and t h e l e f t bronchus p ro ceed s i n f e r i o r l y and l a t e r a l l y b e n e a th
th e i n f e r i o r m arg in o f th e d u c tu s .
The l e f t l a t e r a l p o r tio n o f th e a rc h
i s c o n tin u o u s w ith th e descending a o r ta w hich l i e s t o th e l e f t o f th e
v e r te b r a l column and eso p h ag u s.
The d escen d in g a o r ta i s c ro s se d by th e
l e f t bronchus im m ediately below th e e n tra n c e o f th e d u ctu s and by th e
esophagus i n th e d i s t a l p a r t o f i t s c o u rs e .
The vagus n erv e a g a in c ro s s e s
th e d escending a o r ta i n f e r i o r o r d i s t a l t o th e ju n o tio n o f th e d u ctu s a r ­
te r io s u s and a o r t a .
F ig . 4 4 . A n te rio r v iew . Both
lungs removed and h e a r t p a r t i a l l y
d is s e c te d t o show a n t e r o - p o s te r i o r
c o u rse o f ductus# (Newborn)
-1 3 5 -
The pulm onary a r t e r y a r i s e s l a t e r a l and a n t e r i o r t o th e o r i f i o e o f
th e a sc e n d in g a o r ta and p ro ceed s upward, o b liq u e ly p o sterio rfy an d v e ry
s l i g h t l y la te r a lf e to th e l e f t .
I t p a r a l l e l s th e a rc h o f th e a o r ta t o a
la r g e e x te n t b u t i t i s n o t q u ite a s a rc h e d so t h a t a sm all spaoe e x i s t s
betw een th e i n f e r i o r b o rd e r o f th e a o r ta and th e s u p e r io r b o rd e r o f th e
pulm onary a r t e r y .
The tru n k o f th e pulm onary a r t e r y ascen d s tow ards th e
l e f t and c ro s s e s a n t e r i o r and s u p e r io r t o t h e l e f t a u r i c l e upon w hich i t
re s ts .
The b if u r c a t i o n o f th e pulmonary a r t e r y in to r i g h t and l e f t branohes
u s u a ll y o ccu rs o p p o site th e o r i g i n o f th e innom inate a r t e r y .
T his i s some­
what c lo s e r t o th e m id lin e th a n i s u s u a lly s t a t e d ; th e d u ctu s i s th e r e f o r e
lo n g e r and th e pulm onary a r t e r y s h o r te r th a n d e sc rib e d i n th e l i t e r a t u r e .
The l a t e r a l r e l a t i o n s o f th e pulm onary a r t e r y a re s i m i la r to th o se o f th e
a o rta .
The a sc e n d in g a o r ta form s i t s r i g h t l a t e r a l r e l a t i o n and th e a rc h
o f th e a o r ta i s s u p e r io r .
The a o r ta becomes s e p a ra te d from th e pulm onary
a r t e r y im m ediately proxim al t o i t s b i f u r c a t i o n and rem ains s e p a ra te d from
i t s c o n tin u a tio n , th e d u c tu s , u n t i l th e l a t t e r e n te r s th e d escending a o r ta
1 orn. o r more d i s t a l t o th e o r ig i n o f th e s u b c la v ia n a r t e r y .
The two b ran ch es o f th e pulm onary a r t e r y a r i s e from th e l a t e r a l and
p o s te r io r s u rfa c e o f th e m ain pulm onary tr u n k and c o n tin u e l a t e r a l l y and
i n f e r i o r l y t o th e r i g h t and l e f t lu n g s .
The l e f t pulm onary a r t e r y has
th e c o n tin u a tio n o f th e m ain pulmonary tr u n k , i . e . , th e duotus a r t e r i o s u s
a s i t s s u p e r io r r e l a t i o n .
The l e f t pulm onary a r t e r y a t i t s o r ig i n l i e s a n t e r o - l a t e r a l t o th e
l o f t bronchus upon w hich i t r e s t s a s i t o ro s s e s t o th e r o o t o f th e lu n g .
The l e f t a u r i c l e i s i n r e l a t i o n to th e a r t e r y p o s t e r i o r l y .
The s u p e r io r
o r upper l e f t pulm onary v e in l i e s i n f e r i o r to th e l e f t pulmonary a r t e r y
-1 3 6 -
and bronchus and th e r e f o r e n o t i n d i r e c t c o n ta o t w ith , b u t i n f e r i o r t o
th e d u c tu s a r t e r i o s u s .
The l e f t bronchus i s d i r e c t l y i n f e r i o r t o th e d u c tu s and p a ss e s i n ­
f e r iodyand l a t e r a l l y t o th e l e f t u n d er th e a r c h formed by th e d uotus a s
i t p a ss e s over i t .
The r e c u r r e n t la ry n g e a l b ran ch o f th e vagus n erv e
tu r n s m e d ia lly around th e d uctus an d l i e s betw een i t and th e b ro n c h u s.
The l e f t bronchus i n i t s course to th e r o o t o f th e lung c ro s s e s th e vagus
w hich l i e s p o s te r io r t o i t .
F ig . 45. P o s te r io r view o f duotus
a s i t e n te r s descen d in g a o r t a .
L e ft lung rem oved. (Newborn)
From th e p re c e d in g d e ta i le d d e s c r ip ti o n th e fo llo w in g resum£ may be
made o f th e d u ctu s a r t e r i o s u s i n i t s c o u rse p o s t e r o - l a t e r a l l y t o th e l e f t
t o i t s p o in t o f e n tra n c e in to th e s u i t e r o - l a t e r a l a s p e c t o f th e d escen d in g
-1 3 7 -
a o r ta a b o u t 1 cm. d i s t a l t o th e o r i g i n o f th e s u b c la v ia n a r t e r y and a t
an a n g le l e s s th a n t h i r t y to t h i r t y - f i v e d e g re e s .
(See F ig . 4 5 . ) .
The
e n tra n c e i n t o th e a o r ta i s n o t " a t th e m e d ial b o rd e r j u s t below th e
o r i g i n of th e l e f t s u b c la v ia n a r t e r y . "
(Scammon).
The d u c tu s a p p ea rs
a s th e d i r e c t c o n tin u a tio n o f th e pulm onary a r t e r y j in no specim en was
a d e f i n i t e " d e lim itin g p o in t betw een th e d u ctu s a r t e r i o s u s and pulmonary
a r t e r y " o b serv ed a s s ta t e d by Faber (* 1 2 ).
S u p e rio r to th e d u c tu s and
u s u a lly s e p a ra te d from i t by a sm all c re sc e n t-s h a p e d space l i e s th e a rc h
o f th e a o r t a . . The descen d in g a o r ta f i r s t l i e s s u p e r o - l a t e r a l and th e n
p o s te r io r to th e d u c tu s .
I n f e r i o r l y , p ro c e ed in g a n t e r o - p o s t e r i o r l y , th e
d u ctu s i s i n r e l a t i o n to th e l e f t pulm onary a r t e r y , r e c u r r e n t la ry n g e a l
n e rv e , l e f t bronchus and vagus n e rv e .
To th e l e f t , th e d u c tu s i s i n r e ­
l a t i o n t o th e thymus a n t e r i o r l y and s u p e r io r ly , th e r e c u r r e n t and vagus
n e rv e s and l e f t lung l a t e r a l l y and p o s t e r i o r l y .
The d u ctu s r e s t s upon th e
l e f t bronchus m e d ia lly and i n f e r i o r l y ; and th e m e d ia l s u rfa o e o f th e upper
lobe o f th e l e f t lung p re s s e s l a t e r a l l y a g a in s t and i s
grooved by th e
d u c tu s .
A window was c u t in th e l a t e r a l v /a ll o f th e ductus a r t e r i o s u s i n o rd e r
t o examine i t s i n t e r i o r m a c ro s c o p ic a lly , i n an e f f o r t t o a s c e r t a i n w hether
a rid g e was p re s e n t a t th e a o r t i c e n tra n c e o f th e d u c tu s a s p o s tu la te d by
Strnssinann (F ig . 12, page 3 5 ).
Ho d e f i n i t e v alv e s t r u c t u r e co u ld be found
i n our la rg e s e r i e s o f human m a te r ia l i n th e p o s it io n p o s tu la te d by
S trassm an n .
A p rom inent rid g e however was observed m a c ro s o o p ic a lly in
ab o u t 25yu of th e c a d a v e rs on th e m edial w a ll o f t h e duotus a lm o st midway
betw een th e pulm onary b i f u r c a tio n and i t s a o r t i c e n tra n c e (lioback (* 3 7 ).
The rem ain in g ductus* on m icro sco p ic e x am in atio n , were found to c o n ta in
e i t h e r a low rid g e o r s e v e ra l r i d g e s .
I§ r* »/ !
L.Subci.
D.A.
R.R^
/
F i g . 4 6 . L e ft l a t e r a l v ie w . "Thymus
l i f t e d and window o u t in w a ll o f
duotus to expose i n t e r i o r and r id g e .
RA.
/
L .P A
F ig . 4 7 . Diagram i l l u s ­
t r a t i n g d is s e c tio n in
F ig . 4 6 . (Newborn)
m
D is s e c tio n s im ila r t o F ig . 4 6 . Note
s iz e of rid g e i n d u c tu s and r e l a t i o n
t o l e f t bronchus p a ss in g m e d ia lly and
i n f e r i o r l y . (Newborn}
F ig . 4S . D is s e c tio n s im ila r t o
F ig . 4 6 . Thymus re p la c e d to show
r e l a t i o n to rid g e of d u c tu s .
(Newborn)
-1 3 9 -
HISTOLOGICAL CONSIDERATIONS
T h is fo r m a lin - f ix e d m a t e r i a l was n o t u t i l i z e d t o d is tin g u is h i t s
o y to lo g ic a l s t r u c t u r e beoause o f in a d eq u a te f i x a t i o n r e s u l t i n g from th e
long p e rio d o f tim e e la p s in g betw een th e tim e o f d e a th and fix a tio n *
However, d if f e r e n c e s i n th e a rran g em en t and r e l a t i v e amounts o f smooth
m u scle, f ib r o u s and e l a s t i c c o n n e c tiv e t i s s u e co u ld be determ ined*
Marked d if f e r e n c e s i n th e a rran g em en t o f th e s e t i s s u e s i n th e pulm onary
a r t e r y , th e a o r ta and th e d u ctus vrere r e a d i ly d is c e r n ib le i n th e s e p re p a ­
r a tio n s *
IN THE EARLY FETUS th e in tim a o f th e d uotus i s n arro w and lim ite d
e x t e r n a l l y by a d e f i n i t e in n e r e l a s t i c membrane w hich beoomes more p rom inent
tow ard th e a o rta *
S e v e ra l la y e r s o f smooth m uscle f i b e r s l i e imbedded i n a
lo o se c o n n e c tiv e t i s s u e netw ork form ed m ain ly o f e l a s t i c t i s s u e .
The
smooth m nsole c e l l s a p p e a r s p in d le -sh a p e d when o u t in l o n g itu d in a l s e c tio n ,
and l i e
i n t h i s n etw o rk o f e l a s t i c and w h ite f i b e r s .
In th e V e rh o e ff-
t r i o s i n p re p a ra tio n s a g r e a te r accu m u la tio n o f th e se smooth m uscle c e l l s
may be seen a lo n g b o th s id e s o f th e in n e r e l a s t i c membrane w hich th e r e f o r e
shows up a s a d a rk e r s ta i n in g band o r zone.
However, th e s e s p in d le -s h a p e d
c e l l s a re more numerous w ith in th e m edia a lo n g th e d eep er su rfa o e o f th e
in n e r e l a s t i c membrane.
The m edia o f th e d u ctu s d i f f e r s from t h a t o f th e
pulmonary a r t e r y and o f th e a o r ta i n t h a t i t s smooth m uscle i s p r o p o r tio n ­
a t e l y g r e a t e r i n amount th a n in th e pulmonary a r t e r y and a o r t a , and i n th e
duotus a r t e r i o s u s i t i s a rra n g e d i n th r e e la y e r s c o n s is tin g o f a n in n e r
lo n g itu d in a l, a m iddle o i r o u l a r an d a n o u te r w id e r, more oompaot, l o n g i­
t u d in a l l a y e r .
The in n e r p a r t o f th e o ir o u l a r la y e r i s lo o s e ly a rra n g e d ,
and wide spaoes e x i s t betw een th e b u n d les o f smooth m u sc le .
These sp ac e s
-1 4 0 -
in th e c o n n e c tiv e t i s s u e d e c re a se i n s iz e an d number a s th e p e rip h e ry
o f t h i s c i r c u l a r la y e r i s a p p ro a ch e d .
The la y e r s o f th e m edia become
more uniform and compact n o t o n ly p e r ip h e r a ll y b u t a ls o a t th e pulmonary
and a o r t i c ends o f th e d u o tu s .
The m edia c an n o t be e a s i l y d is tin g u is h e d
from th e a d v e n t i t i a i n t o w hich i t g ra d u a lly m e rg e s.
A d e fin ite e la s tic a
e x te rn a s e p a ra tin g th e m edia from th e a d v e n t i t i a can n o t be d is tin g u is h e d .
However, th e e l a s t i o f i b e r s a r e more numerous i n th e o u te r la y e r s o f th e
media and a d v e n t i t i a .
THE STRUCTURE OF THE DUCTUS IN LATER FETAL LIFE d i f f e r s from th e
more compact arrangem ent o f th e e a r ly f e t u s , i s t h a t a n in c re a s e i n amount
o f m uscle in th e in tim a oocurs so t h a t th e t h i n r e g u la r in tim e o f th e e a r l y
f e tu s becomes t h ic k e r and low tr a n s v e r s e r id g e s a re o c c a s io n a lly p r e s e n t.
The number o f s p in d le -sh a p e d c e l l s had in c re a s e d and th e y a re a rra n g e d in
lo n g itu d in a l l a y e r s .
The lo n g u d in a l la y e r s g ra d u a lly become o b liq u e in
d i r e c t i o n a s th e y ap p ro ach th e r id g e s and w ith in th e s e r id g e s th e y ru n
tr a n s v e r s e l y .
These r id g e s form ed in l a t e r f e t a l l i f e a re composed o f
smooth m uscle ly in g i n a lo o se c o n n e c tiv e t i s s u e strom a covered by a t h i n
e n d o th e lia l l a y e r .
The smooth and r e g u la r c h a r a c te r o f th e lumen o f th e
e a r ly f e t a l d u ctu s i s ohanged i n l a t e r f e t a l l i f e so t h a t i t becomes
g e n e r a lly ir r e g u la r and c o n s t r i c t e d i n th e re g io n i n w hich th e one o r
more in w ardly p r o je c tin g r id g e s a re p r e s e n t .
T h is c h a r a c t e r i s t i c
lo o se arrangem ent o f th e t i s s u e s i n th e w a ll o f th e d u c tu s beoames
more m arked w ith in c r e a s e i n f e t a l a g e , and th u s i t may be deduced
t h a t th e le s s dense arrangem ent i n th e w a ll o f th e d u o tu s makes i t
l e s s a b le t o r e s i s t p re s s u r e s upon i t by n e ig h b o rin g s t r u c t u r e s .
The
duotus o f th e f e t u s i s s u b je c te d to in o re a s e d com pression by th e a d ja c e n t
thymus and lungs a n t e r i o r l y and l a t e r a l l y a s th e y in c r e a s e in s i z e .
The
-1 4 1 -
d u o tu s however i s p re v e n te d from b ein g pushed m e d ia lly by th e more r i g i d
l e f t bronchus*
The d u ctu s t h e r e f o r e s u f f e r s l a t e r a l co m p ressio n w hich
changes th e c i r c u l a r lumen so t h a t i t becomes o v al i n o ro s s - s e o tio n *
The
lumen o f th e ductu6 i n th e l a t e f e tu s i s n o t o n ly com pressed by th e
l a t e r a l p re s s u re s e x e r te d by th e thymus an d l e f t lung b u t i t i s f u r t h e r
re d u c ed by th e in w a rd ly p r o je c tin g rid g e o r rid g e s w hich may th u s p a r t i a l l y
occlude th e lumen*
o f the.
The in tim a , w here i t does n o t e n te r in to th e fo rm a tio n
r id g e s , i s a rra n g e d a s f l a t t e n e d lo n g itu d in a l l a y e r s , th r e e o r
fo u r c e l l la y e r s in th ic k n e s s *
The in tim a i n th e .
f l a t t e n e d a r e a s c o n s is ts
o f e n d o th eliu m and a t h i n in n e r c i r c u l a r a n d a t h ic k e r o u te r lo n g itu d in a l
la y e r o f smooth m uscle and i t i s lim ite d e x t e r n a l l y by th e in n e r e l a s t i c
membrane.
The lo n g itu d in a l la y e r o f th e in tim a i s l e s s compact th a n th e
in n e r c i r c u l a r l a y e r .
A s im ila r lo n g itu d in a l la y e r o f smooth m uscle l i e s
on th e e x te r n a l s u rfa c e o f th e in n e r e l a s t i o membrane and form s th e in n e r­
m ost la y e r o f t h e m e d ia .
The media and e x te r n a o f t h e d u ctu s i n th e l a t e
f e t u s a re s im ila r t o th o s e o f th e e a r l y f e t u s , e x c e p t t h a t a n in c r e a s e in
th e amount o f o o lla g e n o u s c o n n e c tiv e t i s s u e and l o n g i tu d in a l smooth m uscle
has ta k e n p la c e .
T his c o lla g e n o u s c o n n e c tiv e t i s s u e now e x te n d s more d e ep ly
in to th e media and r e s u l t s i n a l e s s compaot arran g em en t o f th e t i s s u e s o f
th e w a ll o f th e d u c tu s .
A la r g e number o f b lo o d v e s s e ls have p e n e tr a te d
th e a d v e n t i t i a of th e duotus le a d in g t o a n in c re a s e d v a s c u l a r i t y and i r ­
r e g u la r arrangem ent o f t h i s p a r t o f th e w a ll*
TIE STRUCTURE OF THE DUCTUS IN THE STILLBORN KEWBORN i s q u ite s im ila r
t o t h a t o f th e l a t e f e t u s .
M o d ific a tio n o f th e h i s t o l o g i c a l s tr u o t u r e of
th e w a ll o f th e d u otus may be d is c e rn e d i n th o s e a r e a s t h a t have been sub­
je c t e d t o p re s s u re by n e ig h b o rin g s t r u c t u r e s .
L o n g itu d in a l sp aces f i l l e d
w ith c o a g u la te d i n t e r s t i t i a l f l u i d , w hich G raper m a in ta in e d i s b lo o d , a r e
-1 4 2 -
p re s e n t.
G raper a c c o u n ts f o r th e p re sen c e o f t h i s m a t e r i a l w ith in th e
w a ll o f th e d u c tu s by assum ing t h a t t e a r i n g h as o o o u rred when a l t e r n a t e
c o n tr a c tio n s an d r e la x a ti o n s o f th e i r r e g u l a r m u s c u la tu re o f t h e lo n g i­
t u d i n a l la y e r s ta k e s p la c e .
G raper f u r t h e r p o s tu la t e s t h a t th e s e lo n g i­
t u d i n a l sp aces f i l l e d w ith w hat he b e lie v e d to be b lo o d , s tim u la te
a c t i v i t y betw een th e blood and t i s s u e c a u sin g th e t i s s u e o f th e media
to form a "th ro m b o tio membrane o f lim ite d th ic k n e s s w hich i s o f e x t r a v a s a te d o r ig i n due t o te a r in g and b le e d in g .”
la y e r s o f th e in tim a to be r a i s e d .
T his p ro c e ss cau ses th e
A ccording t o him d if f e r e n c e s in
p re s s u re w ith in th e th o ra x may a ls o p re d is p o s e th e d u o tu s tow ard ex ­
t r a v a s a t i o n and b le e d in g .
Ee th e r e f o r e m a in ta in s t h a t t h i s e x tr a v a s a tio n
and b le e d in g w ith in th e w a ll o f th e d u ctu s i s norm al and may be due to
i r r e g u l a r c o n tr a c tio n s of th e lo n g itu d in a l m usole la y e r s an d a l s o t o
d if f e r e n c e s i n p re s s u re w ith in th e th o ra x and d u c tu s .
These c o n d itio n s
o b serv ed i n t h e fo r m a lin - f ix e d m a te r ia l o f t h i s s tu d y le a d t o th e con­
c lu s io n t h a t t h i s e x tr a v a s a tio n and b le e d in g i s p ro b a b ly a n a r t e f a c t and
n o t due t o c o n tr a c tio n s o f th e lo n g itu d in a l m usole l a y e r s .
Numerous lo n g i­
t u d i n a l spaces w hioh a re p ro b a b ly o o n n eo tiv e t i s s u e sp aces f i l l e d w ith
c o a g u la te d i n t e r s t i t i a l f l u i d t h a t has p ic k ed up th e s t a i n have a l s o been
observed i n th e w a ll o f th e d u o tu s.
The c o a g u la te d i n t e r s t i t i a l f l u i d
w hich G raper b e lie v e d t o be b lo o d , c o u ld a l s o be observ ed th ro u g h o u t th e
w a ll o f th e d u c tu s .
A g r e a te r accu m u la tio n o f t h i s c o a g u la te d i n t e r s t i t i a l
f l u i d o c c u rre d w ith in th e lo n g itu d in a l s p a o e s .
These sp ac e s were n e v e r
observed t o be p r e s e n t w ith in th e in tim a .
The w a ll o f t h e duotus i n th e s t i l l b o r n newborn c h i l d c o n s is ts o f
th r e e l a y e r s .
The endothelium o f th e in tim a i n th e d u o tu s u n lik e t h a t o f
o th e r v e s s e ls i s d is c o n tin u o u s .
B eneath t h i s en d o th eliu m a la y e r o f
-143
lo n g itu d in a l m uscle f i b e r s i s found t h a t -varies in th ic k n e s s from two t o
sev e ra l o e ll la y e r s .
T h is la y e r i s lim ite d e x te r n a ll y by a la y e r o f
e l a s t i c f i b e r s form ing th e in n e r e l a s t i c membrane o f -varying th ic k n e s s
t h a t i s i r r e g u l a r and wavy i n a p p e a ra n c e .
T h is can be e a s i l y d i s t i n ­
g u ish ed a s co n tin u o u s w ith t h a t o f th e pulm onary tru n k and w ith t h a t o f
th e a o r t a .
The th ic k n e s s o f t h i s in n e r e l a s t i c membrane i s le s s i n th e m id d le
o f th e d u c tu s and may be observed to c o n s is t o n ly of i s o l a t e d e l a s t i c
f i b e r s i n t h i s r e g io n .
The media of th e pulm onary a r t e r y c o n s is ts p red o m in an tly o f e l a s t i o
t i s s u e w hich e x ten d s in to th e d u ctu s f o r a s h o r t d is ta n c e and form s a
s u p p o rtin g strom a in w hich th e smooth m uscle f i b e r s a re im bedded.
The
q u a n tity o f e l a s t i c t i s s u e g r a d u a lly d e c re a se s tow ard th e m iddle o f th e
d u c tu s , th u s r e s u l t i n g i n a m id d le zone c o n ta in in g v ery l i t t l e e l a s t i c
tis s u e .
The e l a s t i c t i s s u e a g a in in c re a s e s in q u a n tity to w ard th e a o r t a
in w hich v e s s e l i t form s th e m ain c o n s t i t u e n t .
From th e fo re g o in g i t may be see n t h a t th e d i s t r i b u t i o n o f e l a s t i o
t i s s u e w ith in th e w a lls o f th e d u c tu s can be c o n sid e re d a s b e in g composed
o f th r e e z o n es, th e one where th e e l a s t i o t i s s u e o f th e pulm onary tr u n k
i s c o n tin u o u s w ith a t r a n s i t i o n a l zone a t th e pulmonary end o f th e
duotus i n w hich th e q u a n tity o f e l a s t i o t i s s u e p r o g r e s s iv e ly d e c re a s e s
u n t i l t h e m iddle t h i r d o f th e d u o tu s i s re a ch e d where t h e r e i s b u t v e ry
l i t t l e tis s u e .
T his m id d le zone i s p r im a r ily m u sc u la r.
The d i s t a l
t h i r d o f th e duotus ( a o r t i c end) a l s o c o n ta in s a t r a n s i t i o n a l zone s im ila r
to t h a t o f i t s pulm onary end w hich c o n ta in s an in c r e a s in g ly g r e a t e r q u a n tity
o f e l a s t i c t i s s u e w hich becomes c o n tin u o u s w ith t h a t o f th e a o r t a .
The
-1 4 4 -
a o r t a i s s im ila r i n s t r u c t u r e t o th e pulm onary a r t e r y c o n s is tin g m ain ly
o f e l a s t i o t i s s u e w h ich s t r u c t u r e l i k e th e pulmonary a r t e r y , i s a ls o
b e t t e r a b le t o w ith s ta n d e x te r n a l p r e s s u r e .
F ig . 50. Lower pow er, 5X photom icro­
grap h o f d u otus a r t e r i o s u s to show
s in g le rid g e p r o je c tin g i n t o lum en.
( S t . B . , 52.7 cm*}
F ig . 5 1 . D uctus c o n ta in in g
m u ltip le r i d g e s . ( s t . B . ,
50.2 c m .). Note d a rk e r
s ta i n in g e l a s t i c t i s s u e o f
pulm onary tru n k and a o r t a .
The e l a s t i c t i s s u e o f th e s e v e s s e ls c o n tin u e s i n t o th e e x t e r n a l la y e r s o f
th e media and a d v e n t i t i a .
There i s a p e o u lia r arran g em en t o f th e e l a s t i c
t i s s u e in th e d u ctu s w hich r e s u l t s i n a w eakness o f th e w a ll o f i t s
m iddle zone, th u s m aking t h i s p a r t o f th e d u c tu s more s u s c e p tib le , th a n
o th e r v e s s e l s , t o p r e s s u r e e x e rte d b y th e n e ig h b o rin g s t r u c t u r e s suoh
a s th e thymus and l e f t lung*
A nother s t r u c t u r a l arrangem en t p e c u li a r t o th e d u ctu s i s t h a t th e r e
a r e many la r g e sp aces ly in g w ith in th e lo n g itu d in a l la y e r s o f i t s m edia*
These a re o f te n f i l l e d w ith o o a g u la te d i n t e r s t i t i a l f l u i d .
In th e new­
b orn th e s e spaces a r e la r g e s and m o st numerous i n th e e x te r n a l la y e r s o f th e
media w hich i s th e r e f o r e l e a s t com pact.
These spaces a re m ost p re v a le n t
-145.
i n th e m iddle zone o f th e d u otus an d i n th e media and o x te rn a o f th e
s u p e r io r m i l o f th e duotus w here i t i s i n c o n ta c t w ith th e u p p er lobe
o f th e l e f t lu n g .
G raper in te r p r e te d th e s e spaoes a s b e in g formed by c o n tr a c tio n o f
th e in n e r la y e r s o f th e m edia j th u s p u llin g th e in tim a and media away
from th e o u te r la y e r s o f th e m edia and e x te r n a , b u t s tu d y o f t h i s m a te r ia l
f a i l s t o su p p o rt suoh an h y p o th e s is .
These spaoes a r e p ro b a b ly a r t e f a c t s
r e s u l t i n g from d e lay e d f i x a t i o n b u t t h e i r d i s t r i b u t i o n however does in ­
d ic a te t h a t th e r e i s a d if f e r e n c e in arran g em en t and s tr e n g th o f th e
v a rio u s re g io n s o f th e m i l o f th e d u c tu s .
(See F ig . 5 2 ) ,
F ig . 52. Low power 5X. M usoulature
o f m edia fo m in g base o f r i d g e . Note
spaoes i n s u p e r io r w a ll.
F ig . 5 3 . Lower power 3X,
s im ila r t o F ig . 5 2 .
A d iff e r e n c e in th io k n e s s o f v a rio u s re g io n s o f th e m i l s o f th e
d uotus m s a ls o o b serv ed , b u t t h i s d if f e r e n c e does n o t alw ays o o in o id e
w ith th e p re sen c e o f a rid g e or s e v e r a l r i d g e s .
The m i l o f th e d uotus
i n c o n ta c t w ith th e l e f t bronchus m e d ia lly i s u s u a ll y th in n e r and more
oom paotly a rra n g e d th a n i s th e o p p o s ite w a ll t h a t l i e s i n c o n ta c t w ith th e
-1 4 6 -
l e f t lu n g .
In same speoimens i t was observed t h a t s e v e r a l la r g e lymph
nodes and some c o n n eo tiv e t i s s u e may be in te rp o s e d betw een th e duotus
and th e l e f t b ro n o h u s.
T his m ed ial w a ll o f th e d u c tu s may t h e r e f o r e be
more oampaot b ecause o f i t s in tim a te c o n ta c t f r ith and th e p re s s u re e x e r te d
by th e l e f t bronchus a s th e duotus p a sse s o v er i t .
T his m e d ia l w a ll o f
th e duotus a g a in becomes more lo o s e ly a rra n g e d to w ard th e a o r t i o end o f
th e duotus*
(See Fig* 5 4 ).
Fig* 54. ( S t i l l b o r n new born).
Lowe/ power 5X. Note d if f e r e n c e s
i n s tr u c tu r e o f m ed ial and s u p e r io r
w a lls and i r r e g u l a r i t y o f lum en.
The l e f t b ronchus th e r e f o r e e x e r ts i t s g r e a t e s t p r e s s u r e a g a in s t th e
m iddle t h i r d of th e ductus and m o d ifie s i t s s tr u c tu r e so t h a t th e duotus
i s more e a s i l y com pressed by th e n e ig h b o rin g s tr u c tu r e s *
The p re se n c e o f a rid g e p r o je c tin g i n to th e lumen o f th e duotus was
n o te d m a c ro s o o p ic a lly by N o b a ck .(’37) who found i t i n a b o u t tw e n ty -fiv e
p e rc e n t o f th e c a se s s tu d ie d .
M ioroscopio e x am in atio n r e v e a ls a g r e a t e r
freq u en o y th a n was observed by him .
I t was p r e s e n t i n th e newborn a s a
-1 4 7 h ig h rid g e in more th a n f i f t y p e rc e n t and a s a lew rid g e o r s e r i e s o f
r id g e s i n th e rem ain d er o f t h i s s e r i e s .
m e d ia l 'w all o f th e duotus in to i t s lum en.
The rid g e p r o je o ts frcro th e
T h is o ccu rs i n th e w a ll o f
th e d u o tu s where i t p a ss e s ov er th e l e f t b ro n c h u s.
T h is sh arp a n g le i n
th e c o u rse o f th e d u o tu s r e s u l t s i n th e s u p e r io r w a ll ly in g in c lo s e r
p ro x im ity t o th e i n f e r i o r w a ll c o n ta in in g th e rid g e and th u s th e lumen
o f th e d u o tu s i s n arro w ed .
(See F ig , 52, Fg. 1 4 5 ).
The rid g e ( o r r id g e s )
i s composed m ainly o f a c o re of sm ooth m u scle, some c o n n e c tiv e t i s s u e and
th e in tim a .
M icroscopic ex am in atio n o f th e h ig h rid g e s re v e a le d an
a rran g em en t o f i t s smooth m usole w hioh i s p e c u li a r t o th e rid g e and con­
tig u o u s p o rtio n s o f th e d u o tu s .
The m u sc u la tu re o f t h i s t r a n s v e r s e rid g e
i s a l s o a rra n g e d tr a n s v e r s e t o th e long a x i s o f th e d u c tu s , b u t a t each
end o f t h e rid g e t h i s m uscle la y e r tu rn s and becomes c o n tin u o u s w ith th e
lo n g itu d in a l m uscle la y e r s o f th e media o f th e duotus i t s e l f .
C o n tra c tio n
o f t h i s arran g em en t o f m u so u la tu re in th e rid g e and w a ll o f th e d u ctu s
s u g g e s ts t h a t suoh c o n tr a c tio n would r e s u l t i n a re d u c tio n of th e c a l i b e r
o f th e lumen o f th e d u c tu s .
In s e v e r a l o f th e new borns t h a t had liv e d f o r a s h o rt tim e some low
rid g e s w ere p a r t i a l l y sloughed o f f . (See F ig , 5 5 ).
F ig , 55. Ridge o f th e
d u c tu s, SOX.
148-
A th e o ry o f c lo s u r e r e s u l t i n g from throm bus fo rm a tio n o r o c c lu s io n by
d e b ris formed i n t h i s manner from th e vra.lls o f th e d u ctu s has been p ro ­
posed by s e v e ra l i n v e s t i g a t o r s .
However, t h i s th e o ry c an n o t be a c c e p t­
a b le due n o t only t o th e e x tre m e ly sm all number o f c a s e s re p o rte d showing
t h i s o o n d itio n , b u t a ls o t o th e q u e s tio n a b le s t a t e o f f i x a t i o n o f th e
m a te ria l.
Go n e LU 3 101 IS
-1 4 9 -
COMCLUSIQNS
D e s c rip tio n s o f th e c o u rse and o f th e to p o g rap h y o f th e d u c tu s
a r t e r i o s u s i n man a s re c o rd e d in th e l i t e r a t u r e d i f f e r w id e ly .
The
p r e s e n t stu d y o f th e d u ctu s a r t e r i o s u s was u n d e rta k e n t o d eterm in e
more a c c u r a te ly th e anatomy of th e d u ctu s and i t s r e l a t i o n s t o i t s
n e ig h b o rin g s t r u c t u r e s .
V ario u s te c h n iq u e s , such a s o rth o d ia g ra p h ic
d raw in g s, photo g rap h y , c a s t i n g , i n je c t io n s and r e c o n s tr u c tio n s were
em ployed.
As a r e s u l t o f th e many o b s e rv a tio n s c a r r i e d o u t upon a
s e r i e s of one hundred and f o r t y f e t a l , newborn and i n f a n t c a d a v e rs th e
g ro ss anatomy and th e h is to lo g y o f th e ductueaire more a c c u r a te ly r e ­
corded and a n e x p la n a tio n o f th e f a c t o r s in v o lv ed i n i t s o lo s u re o f f e r e d .
The d u c tu s a r i s e s as th e d i r e c t c o n tin u a tio n o f th e pulm onary a r t e r y
somewhat f u r t h e r to th e l e f t o f th e m id lin e th a n 1ms been p re v io u s ly d e s ­
c r ib e d .
S ince i t te rm in a te s i n th e d escen d in g a o r t a , i t s c o u rse i s more
d i r e c t l y a n te r o - p o s t e r i o r and i t does n o t ru n s u p e r io r ly to te rm in a te
i n th e d i s t a l p a r t o f th e a rc h o f th e a o r ta a s u s u a lly r e c o rd e d .
The
a rc h o f th e a o r ta l i e s in a more o b liq u e a n te r o - p o s te r i o r p la n e so t h a t
th e e n tra n c e o f th e d u ctu s in to th e a o r ta i s r e l a t i v e l y more f ix e d th a n
i s i t s m id - p o r tio n .
The descend in g a o r ta a t th e e n tra n c e o f th e ductus
i s fix e d t o th e v e r t e b r a l column by c o n n e c tiv e t i s s u e , p le u ra and f a t .
T h e re fo re , when th e lu n g s expand w ith th e o n s e t o f r e s p i r a t i o n , th e l e f t
bronchus i s r a i s e d a g a in s t th e ductus and th e a r c h th e d uotus forms in
i t s course from th e pulm onary a r t e r y t o th e a o r ta beoomes more pronounced.
S li g h t c o n s t r i c t i o n o f th e lumen o f th e d u ctu s r e s u l t s from t h i s s h i f t
in to p o g ra p h y .
-1 5 0 -
A nother im p o rta n t f in d in g c o n c e rn in g th e anatom y o f th e d u ctu s
in th e newborn c h i l d t h a t h as been p re v io u s ly ov erlo o k ed is th e f a o t
t h a t th e d u c tu s e n te r s th e descen d in g a o r ta on i t s a n t e r o - l a t e r a l s u r ­
fa c e .
The m e d ia l w a ll o f th e duotus th e r e f o r e l i e s i n c lo se c o n ta c t
w ith th e a n t e r i o r w a ll o f th e a o r ta where th e d u ctu s e n te r s i t .
The
co n tig u o u s w a l l s , when view ed in lo n g itu d in a l s e c tio n a p p ea r a s a v a lv e ­
l ik e p r o je c tio n in to th e lumen o f th e a o r ta a t th e e n tra n c e o f th e d u c tu s .
Strassm ann based h i s th e o ry o f c lo s u r e o f th e d u ctu s by a " v a lv e ” a t th e
a o r tio e n tra n o e o f th e d u c tu s upon a m isc o n c e p tio n o f th e s ig n if ic a n c e
o f t h i s p r o je o tio n .
However, a v a lv e such as t h a t d e s c rib e d by Strassm ann
has been o b serv ed n o t i n rnan b u t i n th e dog and r a b b i t f e tu s (H am ilton,
Woodbury and 'Woods).
The e n tra n c e o f th e d u ctu s i n to th e a n t e r o - l a t e r a l
w a ll o f th e d escen d in g a o r t a r e s u l t s i n an o v e rla p p in g of th e a o r t i c w a ll
by th e d u c tu s .
A deep groove i s th u s formed on th e l a t e r a l s u rfa c e a t
th e ju n c tio n o f th e s e two v e s s e l s .
T h is groove w hich i s f i l l e d w ith some
a r e o l a r t i s s u e and f a t does n o t c o n ta in th e vagus n erv e a s i s u s u a lly
s ta te d .
The vagus n e rv e and i t s r e c u r r e n t la ry n g e a l b ranch c ro s s th e a o r ta
and d uctus p ro x im al o r m e d ia l to t h i s g ro o v e .
The p o r tio n o f th e duotus
w a ll t h a t o v e rla p s t h e a o r ta te n d s to narrow th e a o r t i c e n tra n c e o f th e
ductus so t h a t th e o p en in g becomes e l l i p t i c a l .
The d u c tu s i s d i r e c t l y in c o n ta c t w ith th e m ed ial s u rfa c e o f th e
upper lobe o f th e l e f t lu n g w hich a s a r e s u l t i s grooved by th e d u c tu s .
Thus i t may be deduc ed t h a t when th e l e f t lu n g expands i t w i l l p re s s
a g a in s t th e l a t e r a l w a ll o f th e d u ctu s and te n d to reduce th e c a l i b e r
o f th e lumen o f th e d u c tu s .
The e n tra n c e o f th e d u ctu s i n t o th e descending a o r ta o c c u rs ab o u t
one c e n tim e te r d i s t a l to th e o r i g i n o f th e l e f t s u b c la v ia n a r t e r y and
-1 5 1 -
n o t d i r e c t l y o p p o site th e o r ig i n o f th e l e f t s u b c la v ia n a r t e r y a s
u s u a ll y re c o rd e d .
The f a c t m ust be c o n sid e re d in a c o n s id e r a tio n of
th e hemo-dynamics o f th e c i r c u l a t i o n d u rin g f e t a l and e a r l y p o s t­
n a ta l l i f e .
More blood w ould be ro u te d t o th e low er p a r t s o f th e body
r e s u l t i n g i n a b e t t e r d i s t r i b u t i o n i n th e amount o f "blood flo w in g to
th e upper and low er re g io n s o f th e b ody.
The d u ctu s a rc h e s over th e l e f t bronchus in i t s o b liq u e a n te r o ­
p o s te r io r c o u rse from th e pulm onary a r t e r y t o th e a o r t a .
I t p a ra lle ls
th e d i s t a l p a r t o f th e a r c h and u p p er p a r t o f th e d escen d in g a o r t a and
i s s e p a ra te d from them by a narrow c r e s c e n t ic s p a c e .
S ince th e ductus
p a r a l l e l s th e a o r ta in th e g r e a te r p a r t o f i t s c o u rs e , th e a n g le i t
forms w ith th e a o r ta where i t e n te r s th e d escen d in g a o r ta i s th e r e f o r e
much le s s th a n th e 33° s t a t e d by llo ed er and o t h e r s .
The to p o g ra p h ic r e l a t i o n s o f th e pro x im al p o r ti o n o f th e d u ctu s
w hich i s th e c o n tin u a tio n o f th e pulm onary tr u n k a re s im ila r t o th o se
o f t h i s tr u n k .
A n te r io r ly and l a t e r a l l y th e p ro x im al p o r tio n o f th e
ductus i s in o o n ta c t w ith th e thym us.
The thymus i s d e e p ly grooved
where i t l i e s in c o n ta c t w ith th e d u c tu s .
A p o r ti o n o f th e l e f t lobe o f
th e thymus e x ten d s p o s t e r i o r l y betw een th e d u ctu s m e d ia lly and th e lung
la te ra lly .
T h is p o rtio n o f th e thymus p la y s a v e ry im p o rta n t p a r t in th e
c lo s u r e o f th e ductus f o r upon e x p a n sio n o f th e l e f t lung th e thymus i s
oompressed betw een th e lung and d u ctu s and th u s e x e r ts a p re s s u re a g a in s t
th e d u c tu s •
Evidence has been p re s e n te d t h a t p re s s u re i s e x e rte d w ith in th e
th o ra x upon th e c o n ta in e d th o r a c ic s t r u c t u r e s by th e expanding lu n g s .
The b ro ad f e t a l thymus undergoes l a t e r a l com pression so t h a t i t becomes
-1 5 2 -
e lo n g a te d and th io k e r a n t e r o - p o s t e r i o r l y .
I t in t u r n p re s s e s a g a i n s t
i t s n e ig h b o rin g s t r u c t u r e s so t h a t a c o m p e titio n f o r space r e s u l t s .
A
s h i f t i n th e to p o g ra p h y o f th e th o ra o ic v i s c e r a oocurs so t h a t th e
innom inate a r t e r y w hich a ro s e t o th e r i g h t o f th e m id lin e i n th e f e t u s
lias been s h if te d to th e l e f t o f th e m id lin e i n th e newborn and i n f a n t
(N oback).
The d u c tu s i s a ls o com pressed by th e thymus so t h a t i t s a rc h ­
in g c o u rse becomes more a b r u p t.
However, th e m ost im p o rta n t e f f e c t upon
th e d u c tu s due t o t h i s com pression by th e thymus i s n o t th e change i n th e
c o u rse o f th e d u c tu s b u t th e com pression and r e s u l t a n t f l a t t e n i n g o f i t s
w a lls .
S tie n o n a ls o p o s tu la te d a to p o g ra p h ic s h i f t i n which th e d u c tu s
changes from a d i r e c t c o n tin u a tio n o f th e pulm onary a r t e r y in th e f e tu s
to a v e s s e l a r i s i n g a t r i g h t a n g le s t o th e pulm onary tr u n k i n th e new born.
T his extrem e s h i f t in p o s itio n was n o t o b se rv e d i n t h i s s tu d y .
He a ls o
d e s c rib e d a g r e a t in c re a s e i n s iz e and le n g th o f th e isth m u s o f th e a o r ta
w hich com presses and re d u c es th e a o r t i c e n tra n o e o f th e d u c tu s in th e new­
b o rn .
These f in d in g s were n o t s u b s ta n tia te d i n t h i s s tu d y f o r no m arked
in c re a s e in s iz e o r le n g th of th e isthm us o f th e a o r ta c o u ld be o b s e rv e d .
The fin d in g s o f t h i s stu d y do n o t a g re e w ith th o s e o f F aber who
b a se s a th e o ry o f c lo s u re upon th e o b s e r v a tio n t h a t th e p o s tn a t a l d u ctu s
becomes th in n e r and t h a t i t run s i n an a r c h o v e r th e l e f t pulm onary a r t e r y
and l e f t b ro n ch u s.
In th e i n f a n t t h a t has liv e d f o r s e v e r a l days th e p o s t - n a t a l d u ctu s
does n o t d i f f e r m arkedly from t h a t i n th e new born.
I t s lumen p r o g r e s s iv e ­
l y becomes n arrow er and shaped somewhat l i k e a n h o u r- g la s s w ith a tr a n s v e r s e
rid g e p r e s e n t on i t s in n e r s u r f a c e .
T his h o u r- g la s s form o f th e lumen of th e p o s tn a t a l d u ctu s can a l s o be
-1 5 3 -
a t t r i b u t e d t o p e c u lia r h i s t o l o g i c a l arrangem ent o f th e e l a s t i o and mus­
c u l a r t i s s u e i n i t s w a ll.
The d u ctu s may be d iv id e d in to th r e e zones;
one a t th e pulm onary end w here th e e l a s t i c t i s s u e o f th e pulm onary a r t e r y
p r o g r e s s iv e ly d e c re a se s a s th e m iddle t h i r d o f th e d u o tu s i s a p p ro ao h ed .
The m iddle zone o f th e d u ctu s c o n ta in s v e ry l i t t l e e l a s t i c t i s s u e and i s
p re d o m in a n tly m u s c u la r.
T h is m iddle zone i s c o n tin u o u s w ith th e a o r t i c
t h i r d o f th e d u otus w hich c o n ta in s an in c r e a s in g ly g r e a t e r amount o f
c l a s t i c t i s s u e u n t i l th e a o r ta i s reach ed w hich i s p red o m in a n tly e l a s t i c .
The m iddle t h i r d o f th e d u ctu s because o f i t s v e ry sm all amount o f e l a s t i c
t i s s u e i s t h e r e f o r e le s s a b le to r e s i s t e x te r n a l p re s s u re th a n i t s p u l­
monary or a o r t i c e n d s.
The tr a n s v e r s e m uscular rid g e in th e m iddle t h i r d o f th e d u ctu s i s
a n o th e r s tr u c t u r e w hich should be c o n sid e re d i n s tu d y in g th e c lo s u r e o f
th e d u c tu s .
T his rid g e p r o je c ts in to th e lumen o f th e d uotus th u s de­
c re a s in g i t s c a l i b e r .
Even though s e v e r a l e a r l i e r i n v e s t i g a t o r s r e p o r te d
th e p re se n c e of lo n g itu d in a l r id g e s p r o je c tin g i n t o th e lumen o f th e d u o tu s ,
i t was n o t u n t i l 1937 t h a t a tr a n s v e r s e rid g e was m en tio n ed by lioback.
A nother p e c u l i a r i t y o f th e w a ll o f th e d u ctu s i s t h a t th e r e i s a d i f ­
fe re n c e in s tr u c t u r e betw een th e s u p e rio r and i n f e r i o r w a lls o f th e d u o tu s .
The s u p e r io r w a ll which i s lo o s e r in s t r u c tu r e th a n th e i n f e r i o r w a ll i s
i n c o n ta c t w ith th e thymus and lung
and is l e s s a b le t o r e s i s t th e
p re s s u re e x e r te d upon i t by th e se o rg a n s .
I n j e c t i o n e x p erim en ts c a r r ie d ou t in t h i s stu d y have a ls o s u b s ta n ­
t i a t e d th e p o s tu la tio n o f a p re s s u re upon th e duotus by th e lu n g s .
The
c o n ta c t o f th e d uctus a g a in s t th e m ed ial su rfa c e o f th e upper lo b e o f
th e l e f t lung a p p a r e n tly due to p re s s u re o f th e d u ctu s a g a in s t th e lu n g
-1 5 4 -
su b sta n c e r e s u l t e d i n a l e s s e r degree o f grow th o f th e a l v e o l i i n t h i s
re g io n th a n i n a l v e o l i n o t s u b je c te d to e x te r n a l p r e s s u r e .
T h is may be
c l e a r l y seen i n th e c o rro s io n p r e p a r a tio n s made by i n j e c t i o n and m ao eratio n .
The new f in d in g s enum erated above le d t o a c r i t i c a l rev iew o f th e
th e o r ie s a tte m p tin g t o e x p la in th e p h y s io lo g ic a l c lo s u re and a n a to m ic a l
o b l i t e r a t i o n o f th e d u ctu s a r t e r i o s u s .
Most o f th e th e o r ie s p re v io u s ly
advanced to e x p la in i t s p h y s io lo g ic a l c lo s u re s t a t e t h a t i t s c lo s u re
occurs a t b i r t h o r w ith in a s h o rt tim e t h e r e a f t e r .
The e x p la n a tio n s
advanced in t h i s p ap er a re based upon th e r e c e n t d is c o v e ry and th e con­
t r i b u t i o n o f t h i s stu d y re g a rd in g a m u scu lar rid g e p r o je c tin g in to th e
lumen o f th e d u c tu s , th e marked la c k of e l a s t i c t i s s u e w ith in th e m iddle
t h i r d o f i t s w a ll, w hich i s f i r s t re c o rd ed h e r e in , c o n s id e r a tio n o f to p o g ra p h io r e l a t i o n s h i p s o f th e th o r a c ic s t r u c t u r e s , and th e p h y s ic a l or
m ech a n ic al f o r c e s r e s u l t i n g from a " c o m p e titio n f o r sp a c e ".
T his compe­
t i t i o n f o r space b eg in s long b e fo re b i r t h and i s g r e a t l y a c c e le r a te d
d u rin g th e n e o n a ta l p e r io d .
E xam ination o f th e thym us, lu n g s , greV t
v e s s e l s , tra c h e a and esophagus in th e newborn shows marked m olding o f
th e s e s t r u c t u r e s due to th e demands of each f o r space in w hich t o m ain­
t a i n i t s form and in c re a s e i n s i z e .
T h is r e s u l t s n o t o n ly in m odifying
th e form o f th e v a rio u s th o r a c ic s t r u c t u r e s , b u t a l s o i n changes in
p o s i t i o n , com pression o f th e w a lls o f v e s s e ls
a id in g in th e o c c lu s io n
o f th e d u c tu s a r t e r i o s u s .
Marked d if f e r e n c e s in form and to p o g rap h y o f th o r a c ic s tr u c tu r e s
e x i s t in th e f e tu s and new born.
The thymus i n th e l a t e f e tu s i s b ro ad
and e x ten d s p o s t e r i o r l y and i n f e r i o r l y fo r a s h o r t d is ta n c e o n ly .
The
-1 5 5 -
lungs l i e i n th e p o s t e r i o r p a r t o f th e p l e u r a l c a v i t i e s and th e r e f o r e
th e r e i s s u f f i c i e n t spaoe a v a il a b le f o r th e thymus t o in c re a s e l a t e r a l l y .
T his c o n d itio n changes however a s th e lu n g s in c re a s e i n volume and occupy
more o f th e p le u r a l c a v i t i e s .
added.
m id lin e .
When r e s p i r a t i o n oommences new fo r c e s a re
The lungs expand tr a n s v e r s e ly and a l s o advance f u r t h e r tow ard th e
The c o m p e titio n f o r space betw een th e lungs and thymus i s th e n
a c c e le r a te d , th e lu n g s r e q u ir in g more space in w hich to expand w ith th e
e s ta b lis h m e n t o f r e s p i r a t i o n .
The thymus undergoes p ro g re s s iv e narrow ing
and m olding w ith th e in c re a s e i n s iz e o f th e lu n g s .
The l a t e r a l w id th o f
th e thymus i s th e r e f o r e g r e a t l y d e crea se d b u t sin c e no d ecrease in thymic
t i s s u e o ccu rs a t b i r t h , i t i n t u r n m ust e x ten d e lse w h e re .
The th o r a c ic
p o r tio n o f th e thymus undergoes l a t e r a l com pression by th e lu n g s and com­
p e n s a te s f o r t h i s by e x te n d in g p o s t e r i o r l y between th e m ed ial s u rfa c e o f
th e l e f t lung and th e p e ric a rd iu m c o v erin g th e r o o ts of th e g r e a t v e s s e ls ,
a o r t i c a rc h and d u ctu s a r te r io s u s *
The u p p er lobe o f th e l e f t lung t h e r e ­
fo re p re s s e s a g a in s t th e thymus w hich in tu r n p re s s e s a g a in s t th e ductus
a r t e r i o s u s and th u s g iv e s r i s e to one o f th e f a c t o r s r e s u ltin g in com­
p re s s io n and o c c lu s io n o f th e d u c tu s.
T hat fo rc e a lo n e xvould n o t s u f f ic e t o compress th e d u ctu s enough to
cause i t s c lo s u r e .
The co u rse and o b liq u e e n tra n c e o f th e d u ctu s in to th e
a o r ta a ls o makes i t more prone t o m o d if ic a tio n by t h i s p r e s s u r e .
The course
o f th e ductus i s more d i r e c t l y a n te r o - p o s to r i o r and e x ten d s f u r t h e r in ­
f e r i o r l y th a n has g e n e r a lly been assum ed.
The n e ig h b o rin g th o r a c ic s t r u c ­
tu r e s th e r e f o r e change in to p o g ra p h ic r e l a t i o n to th e d u c tu s.
The proxim al
h a l f of th e d u c tu s , i . e . , t h a t p o rtio n co n tin u o u s w ith th e pulm onary a r t e r y ,
i s covered by th e thymus s u p e r io r ly and l a t e r a l l y ; th e rem ain d er l i e s
-1 5 6 -
d i r e c t l y in c o n ta c t w ith th e m e d ia l s u rfa c e o f th e l e f t lung w hich i t
v e ry d e f i n i t e l y g ro o v e s.
The e n tra n c e in to th e d escen d in g a o r ta l i e s
on th e a n t e r o - l a t e r a l a s p e c t o f t h i s v e s s e l ab o u t one c e n tim e te r o r
more d i s t a l t o th e o r ig i n o f th e s u b c la v ia n a r t e r y a t th e le v e l o f th e
t h i r d th o r a c ic v e r te b r a and n o t o p p o s ite th e o r ig i n o f th e l e f t sub­
c la v ia n a r t e r y .
S ince th e d u c tu s e n te r s th e a n t e r o - l a t o r a l a s p e c t o f
th e descending a o r ta and n o t on i t s m e d ial a s p e c t a s has been commonly
s t a t e d i n th e l i t e r a t u r e , i t s e n tra n c e form s an o v a l o r e l l i p t i c a l open­
in g t h a t fa c e s th e l e f t lu n g .
YJhen th e l e f t lung expands, i t p re s s e s
l a t e r a l l y a g a in s t t h i s e l l i p t i c a l a o r t i c e n tra n c e o f th e duotus and
f l a t t e n s th e l a t e r a l w a ll o f th e d u ctu s a g a i n s t i t .
T h is com pression
and r e s u l t a n t f l a t t e n i n g o f th e w a ll o f th e d u ctu s w i l l cause th e d i s t a l
p o r tio n o f th e l a t e r a l w a ll o f th e d u c tu s t o a c t in a v a lv e - lik e manner
th u s narrow ing th e f u n c tio n a l lumen o f th e d u c tu s w hich e n te r s th e a o r t a .
The l e f t bronchus p a sse s o b liq u e ly i n f e r i o r l y and l a t e r a l l y under
th e duotus and th u s serv es as a fu lcru m ovor w hich th e d uctus m ust bond
in i t s course to re a c h th e a o r t a .
The l e f t bronchus th e r e f o r e a c t s as
a p a s s iv e fo rc e p re v e n tin g th e ductus from s h i f t i n g i t s p o s it io n in
re sp o n se t o th e com pressing f o r c e s e x e r te d upon i t .
The d u ctu s w i l l
th e r e f o r e s u f f e r com pression due to th e a c ti v e s u p e r io r and l a t e i 'a l
p re s s u re o f th e thymus and th e l a t e r a l p r e s s u r e of th e luxxg a g a in s t th e
m e d ial r e s is ta n c e to th e s e p re s s u re s by th e l e f t b ro n c h u s.
These fo rc e s however a re augmented by s t i l l a n o th e r f a c t o r w hich a id s
in prod u cin g t h i s c lo s u r e .
A tr a n s v e r s e r id g e o f v a lv e - lik e n a tu r e was
found p r o je c tin g i n t o th e lumen o f th e d u c tu s ab o u t midway betw een th e
b eg in n in g o f th e d u ctu s a t th e b i f u r c a tio n o f th e pulm onary a r t e r y and
-1 5 7 -
i t s te r m in a tio n a t i t s e n tra n c e in to th e d escen d in g a o r ta in e v ery
specim en exam ined.
T his rid g e ( i n some c a s e s , s e v e ra l r id g e s ) i s an
in grow th o f th e in n e r lo n g itu d in a l smooth m uscle la y e r o f th e -wall o f
th e d u c tu s where i t p a ss e s over th e l e f t b ro n c h u s.
T h is rid g e i s a
d e f i n i t e s tr u c t u r e t h a t i s a lre a d y p re s e n t d u rin g f e t a l l i f e and i s
n o t a f o ld r e s u l t i n g from k in k in g o r s h i f t i n g i n th e p o s itio n o f th e
d u o tu s .
The arrangem ent of th e lo n g itu d in a l m uscle la y e r a id s in i n ­
c r e a s in g th e s iz e o f t h i s r id g e .
The re d u c tio n o f th e f u n c tio n a l
c a l i b e r o f th e lumen o f th e d u ctu s by t h i s rid g e m ust th e r e f o r e have
begun sometime p re v io u s t o b i r t h and should be c o n sid e re d when th e
p ro c e ss e s r e s u l t i n g i n p h y s io lo g io a l c lo s u re and a n a to m ic a l o b l i t e r a t i o n
o f th e lumen a re c o n s id e re d .
The arrangem ent and q u a n tity of e l a s t i c and m u scu lar t i s s u e w ith in
th e w a ll o f th e d u ctu s i s a n o th e r v e ry im p o rta n t f a c to r t o be c o n sid e re d
i n p o s tu la tin g a th e o ry o f c lo s u r e .
The e l a s t i c t i s s u e does n o t e x ten d
in to th e m id d le re g io n o r zone o f th e d u c tu s .
T h is zone c o n s is ts m a in ly
o f m u scu lar t i s s u e and i s th e r e f o r e l e s s a b le th a n th e pulm onary a r t e r y
o r th e a o r t a t o r e s i s t e x te r n a l p r e s s u r e .
C lo su re of th e d u c tu s o ccu rs
f i r s t in t h i s re g io n so t h a t th e lumen assumes th e shape o f an h o u r - g la s s .
The p e c u lia r arrangem ent of th e s t r u c t u r a l e lem en ts o f th e w a ll o f th e
ductus f a c i l i t a t e s th e r e te n tio n o f th e shape t o w hich th e d uotus i s com­
p re s s e d .
The e l a s t i c i t y o f th e w a ll o f th e d u c tu s i s l o s t and th e r e f o r e
when th e lu n g expands a g a in s t th e d u c tu s, th e d u c tu s does n o t a g a in e x ­
pand to i t s form er shape a f t e r th e lung c o n t r a c t s , b u t te n d s t o r e t a i n
th e f l a t t e n e d shape im p ressed upon i t by th e lu n g .
C o n tra c tio n o f th e
la rg e amount o f m usoular t i s s u e i n t h i s re g io n w i l l overcome any te n d en c y
-1 5 8 -
o f th e w a lls of th e duotus t o re g a in t h e i r o r i g i n a l shape so t h a t th e
o lo s u re i s g r e a t l y f a c i l i t a t e d n o t o n ly by th e la c k o f e l a s t i c t i s s u e
in t h i s re g io n b u t a ls o by th e in c re a s e d amount o f m u scu lar t i s s u e .
A s e r i e s o f m easurem ents
was a ls o made o f th e d u o tu s a r t e r i o s u s ,
pulm onary tr u n k , l e f t pulm onary a r t e r y and a rc h o f th e a o r ta above and
bolow th e e n tra n c e of th e d u c tu s .
The d iam eter o f th e d u ctu s i s s l i g h t l y
l e s s th a n t h a t o f th e pulm onary tru n k or th e d escending a o r ta and a lm o st
tw ic e t h a t o f th e l e f t pulm onary a r t e r y .
The blo o d sh o u ld t h e r e f o r e te n d
t o flow more d i r e c t l y from th e pulm onary tr u n k th ro u g h th e d u c tu s i n t o th e
d escen d in g a o r ta s in c e th e t o t a l c a l i b e r o f th e r i g h t and l e f t pulm onary
a r t e r i e s i s c o n s id e ra b ly s m a lle r th a n t h a t o f th e d u c tu s .
C losure o f th e ductus oan a ls o be a t t r i b u t e d to changes i n b lo o d
p re s s u re r e s u l t i n g in an a l t e r a t i o n i n th e flow th ro u g h th e d u ctu s*
These
blo o d p re s s u re changes a re b ased upon f a c t o r s such a s th e i n i t i a t i o n o f
r e s p i r a t i o n or stoppage of th e p la c e n ta l c i r c u l a t i o n .
The i n t r a t h o r a c i c
( i n t r a p l e u r a l ) and in tra p u lm o n a ry p re s s u re s and t h e i r e f f e c t s have n o t
been e x te n s iv e ly s tu d ie d .
A t b i r t h th e expansion of th e c h e s t in c re a s e s th e d ia m e te rs o f th e
th o r a c ic c a v ity and c o n se q u e n tly g ra d u a lly in c re a s e s th e n e g a tiv e i n t r a ­
p l e u r a l p re s s u re s in c e th e lu n g s do n o t expand s u f f i c i e n t l y t o c o m p le te ly
f i l l th e p le u r a l c a v i t i e s a t b i r t h .
A p ro g re s s iv e in c re a s e i n th e number
o f a l v e o l i expanding w ith a i r occu rs f o r same tim e a f t e r th e o n s e t o f
r e s p i r a t i o n (p ro b a b ly f o r days or even weoks) u n t i l th e lu n g s a r e "com­
p l e t e l y " expanded.
The e x p an sio n o f th e a l v e o l i and f i l l i n g o f th e
lu n g s fo llo w s a d e f i n i t e p a t t e r n .
A t b i r t h th e n e g a tiv e i n t r a p l e u r a l
and in tra p u lm o n a ry p re s s u re s a r e g r e a t e s t f o r th e lu n g s a re l e a s t e x -
-1 5 9 -
panded,
When th e t h o r a c i c c a v ity i s expanded a t th e f i r s t i n s p i r a t i o n
a i r e n te r s th e lu n g s and expands o n ly th e a l v e o l i n e a r th e h ilu n and
th o se in th e a n t e r i o r b o rd e rs o f th e lu n g s .
T h is f a i l u r e o f th e lu n g s
to c o m p le te ly expand -w ill t h e r e f o r e in c re a s e th e n e g a tiv e p r e s s u r e .
As th e lu n g s c o n tin u e p r o g r e s s iv e ly t o expand and f i l l more o f th e
p le u r a l o a v i t i e s th e n e g a tiv e p re s s u re i s d e c re a se d s in c e le s s o f th e
p le u r a l c a v i t i e s e x is t s and th e n e g a tiv e p re s s u re w i l l te n d to ap p ro ach
a p o s itiv e p r e s s u r e .
The n e g a tiv e p re s s u re w ould th e r e f o r e be g r e a t e s t
a t b i r t h and p r o g r e s s iv e ly d e crea se u n t i l th e a d u lt c o n d itio n i s re a ch e d
in which th e n e g a tiv e i n t r a p l e u r a l p re s s u re i s r e l a t i v e l y c o n s ta n t and
p r o p o r tio n a l t o th e degree of e x p an sio n and c o n tr a c tio n of th e lu n g s and
th o r a x .
T h is n e g a tiv e p r e s s u r e xvill a l s o have a d i r e c t b e a rin g on th e c lo s u re
o f th e d u c tu s a r t e r i o s u s .
Since th e
n e g a tiv e p re s s u re i s g r e a te r a t b i r t h
th e d uctus w i l l be com pressed l a t e r a l l y by r e l a t i v e l y le s s p re s s u re th a n
su b se q u e n tly when th e i n t r a p l e u r a l p re s s u re i n c r e a s e s .
T h is in c re a s e d
e x te r n a l p r e s s u r e , co u p led w ith th e d e c re a se i n blood flo w th ro u g h th e
ductus due t o th e e x p a n sio n o f th e lu n g s, and co n seq u en t in c re a s e d blo o d
flow th ro u g h th e pulm onary a r t e r i e s w i l l a id i n c lo s u re o f th e d u c tu s .
Since th e flow th ro u g h th e d u ctu s is d e c re a sin g a c o rre sp o n d in g f a l l in
i n t e r n a l p re s s u re w i l l r e s u l t and th e r e f o r e le s s o p p o s itio n to th e ex­
t e r n a l i n t r a t h o r a c i c p re s s u re and com p ressin g f o r c e s e x e rte d by th e lung
and thymus w i l l c o n tin u e .
The d u ctu s w i l l th e r e f o r e te n d to be more
e a s i l y com pressed and i t s p h y s io lo g ic a l c lo s u r e f i n a l l y r e s u l t .
P h y s io lo g ic a l c lo s u re o f th e d u c tu s a r t e r i o s u s i s th e r e f o r e undoubt­
e d ly due to many f a c t o r s , among xvhich m ust be in c lu d e d th e a n t e r i o r and
-1 6 0 -
l a t e r a l p re s s u re e x e r te d by th e thymus and th e l a t e r a l p re s s u re o f th e
l e f t lung a s th e y te n d t o com press th e w a ll of th e d u ctu s a g a in s t th e
e l l i p t i c a l a o r t i c o p e n in g .
S in ce th e l e f t bronchus more or le s s f ix e s
th e d u c tu s a r t e r i o s u s i n p la c e , i t cau ses th e d u ctu s t o cu rv e over i t as
i f i t were r e s t i n g upon th e edge o f a fu lc ru m .
The i n t e r n a l l y p r o j e c t ­
in g tr a n s v e r s e r id g e is situ a ted l a t e r a l and above th e l e f t bronchus a c t s
a s th e sh a rp edge o f t h i s fu lcru m and t h e r e f o r e p la y s a v i t a l r o le i n
d e c re a sin g th e c a l i b e r of th e lum en.
The la c k o f e l a s t i c t i s s u e and
p e c u li a r arrangem ent o f m u scu lar t i s s u e w ith in i t s w a lls makes th e d u ctu s
more s u s c e p tib le t o com pression and c o n s t r i c t i o n .
The p ro c e ss h e r e in d e so rib e d r e q u ir in g d e v elo p m en ta l, m ech an ical
and p h y s ic a l changes th e r e f o r e does n o t ta k e p la c e w ith in a s h o r t p e rio d
o f tim e b u t i s o f c o m p a ra tiv e ly long d u ra tio n b eg in n in g d u rin g f e t a l l i f e
and te r m in a tin g sometime, o c c a s io n a lly months a f t e r b i r t h .
The c lo s u re
o f th e d u ctu s a r t e r i o s u s th u s o ccu rs a s b u t one o f many changes talcing
p la c e in th e th o ra x fo llo w in g b i r t h a s a r e s u l t o f "a c o m p e titio n f o r
space" by th e c o n ta in e d s tr u c tu r e s and th e f o r c e s th e y e x e r t upon each
o th e r in t h e i r a tte m p t t o grow and expand.
SUMMARY
-1 6 1 -
1.
A d e s c r ip ti o n o f th e to p o g ra p h ic r e l a t i o n s h i p s , m ic ro sco p io
anatcany, s i z e , shape and co u rse of t h e d u ctu s a r t e r i o s u s i n th e
fe tu s , s t i l l b o r n , new born, i n f a n t and oh ild ,
2.
i s re c o rd e d .
The d i r e c t i o n o f th e co u rse o f th e d u ctu s a r t e r i o s u s i s more
d i r e c t l y a n t e r o - p o s t e r i o r and e x ten d s f u r t h e r i n f e r i o r l y th a n i s
u s u a lly d e s c rib e d .
3.
The d u c tu s a r t e r i o s u s e n te r s th e descending a o r ta 1 cm. d i s t a l to
th e o r i g i n o f th e s u b o la v ia n a r t e r y from th e a o r t i c a rc h i n s te a d
o f j u s t o p p o site t o th e o r ig i n o f t h i s v e s s e l a s d e s c rib e d in th e
lite ra tu re .
4.
The d u ctu s a r t e r i o s u s e n te r s th e descending a o r ta on i t s a n te r o ­
l a t e r a l a s p e c t and n o t th e m e d ia l s u rfa c e of th e a rc h o f th e a o r ta
a s d e s c rib e d i n th e l i t e r a t u r e .
5.
A tr a n s v e r s e m u scu lar rid g e o r rid g e s has been found i n th e m e d ia l
•wall o f th e d u ctus ab o u t midway betw een i t s b e g in n in g a t th e p u l­
monary b i f u r c a t i o n and i t s te rm in a tio n i n th e d escen d in g a o r t a * t
6.
T his rid g e has been found by m ic ro sco p ic ex am in atio n t o be p r e s e n t
in a lm o st e v e ry specim en s tu d ie d and n o t tw e n ty -fiv e p e r c e n t a s
p o in te d o u t by Koback who re p o rte d h is m acroscopic f i n d i n g s .
7.
These r id g e s u s u a lly c o n s is t o f in tim a and m e d ia .
The in tim a may
a ls o form low r i d g e s .
8.
The in n e r lo n g itu d in a l m uscle la y e r s of th e m edia becomes o b liq u e
a s th e rid g e i s approached and tr a n s v e r s e w ith in th e r i d g e .
These
la y e r s of m uscle may on c o n tr a c tio n narrow th e d iam eter o f th e
lumen o f t h e d u ctu s and a i d in c lo s in g i t .
The rid g e o r r id g e s
a re u s u a lly lo c a te d in th e m iddle o f th e duotus*
-1 6 2 -
9.
The amount o f smooth m usole i s g r e a t e s t i n th e m iddle t h i r d o f
th e d u c tu s .
An a l t e r a t i o n o f l o n g itu d in a l and c i r c u l a r smooth
m uscle la y e r s e x i s t s w i t h i n th e w a ll o f th e d u c tu s .
10.
The d u ctu s can be d iv id e d h i s t o l o g i c a l l y in to th r e e zones; one
t h i r d a t th e pulm onary end where th e e l a s t i o t i s s u e o f th e p u l­
monary a r t e r y p r o g r e s s iv e ly d eo reaso s a s th e m id d le t h i r d or
zone i s reached w hich c o n ta in s v e ry l i t t l e e l a s t i c t i s s u e .
T his
m iddle zone is c o n tin u o u s w ith th e a o r t i c t h i r d o f th e d uctus w hich
c o n ta in s an in c r e a s in g ly g r e a te r amount o f e l a s t i c t i s s u e u n t i l th e
a o r ta i s reach ed w hich i s p red o m in an tly e l a s t i c .
1 1.
L am ination and s in u s fo rm a tio n was observed i n th e o u te r la y e r s o f
th e m e d ia .
T h is a r t e f a c t was p ro b ab ly caused by d e lay e d f i x a t i o n
r e s u l t i n g in a p a r t i a l s e p a r a tio n of th e in n e r
1 2.
and o u te r l a y e r s .
The d u ctu s a r t e r i o s u s i s covered s u p e r io r ly and l a t e r a l l y by th e
thymus w hich organ in tu r n i s covered l a t e r a l l y and a n t e r i o r l y by
th e m e d ia l s u rfa c e o f th e l e f t lu n g .
13.
A c o m p e titio n f o r space among th e th o r a c ic v is c e r a e x i s t s d u rin g
f e t a l l i f e and t h i s i s i n t e n s i f i e d w ith th e e s ta b lis h m e n t o f r e s p i r a ­
tio n .
The thymus i s com pressed l a t e r a l l y and fo rc e d p o s t e r i o r l y a -
g a in s t th e d u c tu s .
14.
The l e f t lung p re s s e s th e l a t e r a l w a ll o f th e d u ctu s a g a in s t th e
in t e r n a l rid g e and th e l e f t b ro n c h u s.
The l e f t lung a ls o com presses
th e o b liq u e a n t e r o - l a t e r a l e n tra n c e in to th e d escending a o r ta and
shows a d e f i n i t e g ro o v in g .
1 5.
C losure o f tine d uctus b e g in s d u rin g th e l a t t e r p a r t o f f e t a l l i f e
and i s com pleted sometime a f t e r b ir t h *
163-
16# Some o f th e f a c to r s in v o lv e d in c au sin g c lo s u r e of th e d u ctu s a r t e r i o s u s a re s
th e p re s s u re of th e thymus a n t e r i o r l y and l a t e r a l l y ,
th e p r e s s u r e o f th e expanding l e f t lu n g ,
th e f i x i t y o f th e p o s i tio n o f th e "bronchus over w hich th e
d u ctu s a r c h e s ,
th e o b liq u e a n t e r o - p o s t e r i o r c o u rse o f th e a rc h o f th e a o r t a ,
th e p re sen c e o f th e tr a n s v e r s e rid g e on th e m ed ial w a ll
o f th e ductus p r o je c tin g in to i t s lumen,
th e o b liq u e e n tra n c e o f th e d u ctu s i n t o th e a n t e r o - l a t e r a l
w a ll of th e descending a o r t a ,
th e e l l i p t i c a l opening o f th e a o r t i c e n tra n c e of th e d u c tu s,
c o n tr a c tio n o f th e lo n g itu d in a l m uscle la y e r s o f th e media
and tr a n s v e r s e m uscle f i b e r s of th e rid g e le a d in g to
narrow ing and c o n s t r i c t i o n o f th e lum en,
la c k of e l a s t i c t i s s u e in th e m iddle t h i r d o f th e d u c tu s ,
f a l l i n p re s s u re w ith in th e ductus due t o expansion o f th o
pulm onary b ed .
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