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The vascularity of the cerebral cortex in a specimen of apteryx. Additional evidence of the presence of a homologue of mammallian neocortex

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THE VASCULARITY OF THE CEREBRAL CORTEX IK
A SPECIMEN O F APTERYX
ADDITIONAL EVIDENCE OF THE PRESENCE OF A ROMOLOGUE OF
MAMMALIAN NEOCORTEX .
13. IIOENE CBAIGFIE
Departmert of Biology, University of Toronto
TIlUEE FIGUBES
In a recent publication (Craigie, '39) there has been presented a description of certain small superficial laminated
areas in the cerebral hemisphere of the kiwi, together with
cozlsiderations indicating that these are vestiges of laminated
cerebral cortex similar in general structure to that in lower
mammals. The present communication concerns the richness
of the capillary supply in the most distinctly laminated region
of this cortex, which is situated on the ventrolateral surface
of the hemisphere near the occipital end, just lateral to the
hippocampal fissure ( '29, fig. 1). At the same time the
capillary supply in the dorsal, non-laminated thickening of
the pallium, the cortex mediodorsalis, hyperstriatum superius, or Sugittdwdst, and in the archicortex will be placed
on record.
MATEBIA'L AND METHODS
Only one specimen in which the capillary supply could be
studied has been available, this being the same in which the
laminated cortex itself was described. It is a brain of
Apteryx said to be A. australis, but probably the variety
mantelli. The brain was received by the late Dr. J. I. Hunter
from the Dominion Museum, Wellington, New Zealand,
through the good offices of Dr. W. I?. Gowland, of the University of Otago, and was presented to the writer by Dr. A. L.
Burkitt, of the University of Sydney. The brain was mi
SO9
THF ANATOMICAL RECORD. VOL. 43, XO. 8
AUQWST, 1929
210
E. HOItPI'F. (WAIGIE
into trans\-erse sections which were mounted a s two series,
oiic: heiiig stained with carbol thionin, tlie other with iroll
liaematoxyliii. In the latter series ihe blood \-essels arc
obscrrcd t o he gorged with blood which has i ~ ~ t a i i i ead jetblack stain, so that the preparations are as good as if they
liatl beeii injectcd.
3Teasurements of the vascularity Iiave conseqiiently I)een
made in all tlie regions of the brain stcm ancl cerchellnm
wlierr similar mcasurenients Iiavc previoiisly been carried
out by the writer ('20, '26) i n other aiiimals, as well a s iii
x-arious parts of the cerebral hemisphere. As the significaiicc
of t liese caniiot be consiclcred ;tdvantaqonsly until measuremrrits upoii a sei*ies of specimens of some other avian type
:we awilahlc for (~ompizrison,011157 ilic results for the ~)alliurn,
in \riew of tlic unusual developwliicli are of special inter
mciit of this region, will be rcported ;it Ilic present timc.
Regarding the c*omplcteness of tlic demonstration of the
vessels, a11 that can be said is that tlic iiniform scattering of
visible capillaries in all p a r t s of tlie specimen aiid the general resemblance of tlie seciioiis to tliose of well-injected
brairis of other animals seem to indicate that at least a
reasonable approach to completciiess has been attained. An
a ])ology is pcrliaps needed l o r bnrdening the literature with
measnrcments made i n a single specimen only. The rarity of
tlie material ancl tlic interest of the observations which h a r e
been made upon it are the jnstificatiou of this aclion.
0 6 S E IZVATIONS
The sections being 30 p in thickness, the direct measnrerneiits are not comparable with those which liavc been made
iii other iypes, wlicre sections 30 i i thick have been used in
all cases. (.'onsequcntly, the original figures have been
reduced to represent the total length of the vessels in 3 x
x 200 c.p of tissue and also to a basis of (100 p ) " of
tissue 011 the slide, thesc figures being given in the acvornl);iny\.ing table. K r c n these results caiinot be compared directly,
howrver, with those in other cases, as correction caiinot be
made f o r shrinkage of the material, measnrcments of thc
211
VASCULARITY O F T H E CEHEBRBT, COIlTES
specimen in the fresh condition not being available. The
treatment of the material has bcen too complicated for a
worth-while estimate of tlie shrinkage to be made on tlie basis
of other cases. Consequently, only thc relation between the
different parts can be regarded as significant. It seems safe
to remark, however, tliat the vascnlarity in general is markedly lower than in the adult albino rat, but significantly
highcr than in the dogfish ( '28). Its excess over that in the
ratfish ( '27) is probably sigiiificant also.
VnrcuTority of tlic ~ m l l i u mi
n
Hyperstriatuin snperius
Neocnrtex (ventrolateral)
L. zoiialis. I
L. pyramidalis. I1 aiid 111
L. gran. int. I V
L. ganglionaris. 5'
L. multiformis. V I
B rchicortex-Ammoii 's
formation
L. zoiialis
Pyramids
A4rchicortex-ffaseia dentata
L. zoiialis
Cell layer
(c
bruin of .fptery.z ( n o t corrected f o r ~ l i i i n L n ( j e )
4.0
4.3
4.0
1593
447
1167
1240
1295
956
8GO
327
347
362
268
241
977
1365
274
382
864
1121
242
314
The diameter of the capillaries, which is also shown in the
table, is about tlic same as that in the ratfish, being thus less
than in the dogfish, but greater than in the albino rat.
As in the fishes, vascularity of the forebrain tends to be
rather low as compared with that in the brain stem. The
true laminated cortex, moreover, both archi- aiid neocortex,
is definitely poorer than the non-laminated pallial thickening,
the hyperstriatum superiusl (see table). It is poorer than the
* Area 6 of Rose (Jour. f. Psyrh. 11. Neur., '14) ; liypcrstriatuin accessoriuin of
Huber and Ciosby (Jour. Camp. Neur., '29).
iieostrinturn (\vhicli, of course, is also pallial iii origiii) aiicl
the mesostriatum, and its richer lavers arc abont. 011 a psi*
with the archistxiaturn.
The point. to which it is clesirecl to tlixw sljccial attentioii
at present is the relatioil of the different layers of the area
which is described as neocortex2 ( ’29). These arc rcprescnted graphically in figure 2, a i d a comparison of the latteiwith figure 1will shorn at a glance that, while the differences
hc,twccu the layers a r e quantitatively less than in the albiiio
rat, tlic general relations arc essentially identical. I n parIicnInr, the s r e a tcr vascularity of tlie siipragraiinlai* a~ cornlraretl with tlic snbgraiiulai~l a ~ - e may
~ s bp noted.
4 800
4000
3000
I
m
m
P
I
1400
I000
800
I
1-III
E
P
2
Fig. I
Giaphir rcpresentatioii of the capillnrg- richness of the Tarious laminae
of the temporal cortex of t h e a l t i n o rat at tneiitp days o f age
(
0
-
0)
at a Scar or more (.----.).
The Arabic iiuinerals represent the
Length in inicra o f the capillaries in 1 X 189’ X %I0 r.,u of tissue on the slidr.
‘J’hr Roman ~iuiiirralsrepresrnt the lamiiiac of the cortex.
Fig. 2 Graphic representation of the capillary richness of tlir various lainiiiae
111 the veiitrolatcral p a r t o f tlie ‘iteo~ortrx’of &4ptergx.
:iiici
’ IIubcr ant1 Crosby consider this probahly t o he pyriforni-lobe cortex. This
n i i d t l r d (picstion is iliscusserl hy the prwent mritcr in tii-o other papws
( ’29, ’29 a ) .
YASC LTIACITP OF T H E CEItEBItAL COIlTEX
213
In drawiiig these graphs the measurements of the length
of the capillaries in x 1 8 Y x 200 c.p of tissue n o t corrected
f o r shrinkage have been used. The twenty-day-old rats are
males (’25), the adults are of both sexes and some are o i
uiikiiomn age, the data being the averages f o r all the adults
studied (’21). I n figure 1 each square on the ordinates represents 200 p, vvhile in figure 2 each square has been made
to represent o11l~7100 1-1, in order to bring out the rclations
more clearly.
+
Pig. 3 Photornicrograph of part of the veiitrolateral
sliomii~gthe laiiiiiiae and t h e capillaries. X 5 6 t .
neocortex’ of Apteryx,
Thus the relative vascularity of the lamiiine supports the
view that these may be regarded as homologons with the
layers of the mammalian neocortex. Their relative poorness
in capillaries as compared with other parts of the brain may
possibly be correlated with the small functional importance
which they may be presumed to have in the only bird where
they are linown to occur at all.
Regarding the vascularity of the archicortes, no cwmrnciit
of value can be made in the absence of any inform a t’ion as
t o its condition in other animals.
214
In a single specimen of tlic hrain of Apteryx the vascularity is, in general, much less than in the adult albino rat,
tliougli greater than in the dogfisli.
The diameter of tlic capillai*ies is also intermediate
s,
hetween those recorded f o r the two latter ~ ~ i i r n a l being
about the same as in tlic ratfish.
Tlie vascularity i n the forebrain is relatively low and that
of the c ~ r c b r a lcortex is lower than iii most 1)arts of the
corpus st rintum. Rreasnrements in both archi- and neopallial
rcigioiis ai‘c iwoided.
The layers of tlie small laminated area which has beeii
tlesc3rik)ed a s iicocortes have essentially the same mutual relation in point of vascularity a s those of the rieocortex in tlic
rat, tlir zone representing the in teriid granular layer being
riclicst and tlie sul)ragraiinlar being richer than the subgraiiulnr laminae. Thus tlic quantitative relations of the
capillary supply provide adtlitioiial evidence in favor of tlie
view that tliesci layers a r e proliablj- homologous with those
of t h e mammalian ncocortes.
LITERA’J’ITRE CITED
(“‘RAICIE, 12.
_____
___
IIORXE 1920
On tlie rr1:itiTe xasculaiitJ- of rarioiis parts of llie
triii of the all)iiio rat. Jour. Conip. Nwir., \01. 31,
1921 Tlic ~ a w i i k ~ i i tof
y tliv ccrel,ral cortrk of t h r :tlbnio rat.
.Joiir. Coiiip. Kein., w l . 33, pi?. 193-214.
7933 €’ostiirtt;il ciiaiigcs 111 ~ : i ~ c i i l a ~iiii t tlic
~ crrebral c*ortc.r of
tlie inalc :tll~iiiorat. .Jour. C’oiiip. Krur., vol. 39, pp. 3 0 1 4 2 4 .
1926 Tlir i n x c u l n r i t y of the vagiis riurlei aiid of the adjacent
reticuhr foririatioii i n thc albino rat. .Joiii. (‘omp. Neur., 101. 42,
pp. 37-68.
1927 Kotes oii tlir xascwlar siipplp iii the I)rain of :t holoreplialiaii,
IIydrolagiis (Cliiinarra) collir.1.
.Tour.
Coinp. Kcur., 101. 43,
_____I
pp. 193-200.
1928 The xasculnrity of vayioit> part? of the central iierious
of the dogfish, Rqualns sucklii. Jonr. (’oinp. Kcur., T 01. 46, pp. 97-123.
____
1929 The ecrebral cortcr of ,-2pteryx. Exidence that the avi:ru
iieorortex lm.; bccii rediiccd from a iiiultilainiiiar condition. Anat.
Anz. (In ~ ) r c s s . )
_ - .___
1929 :L Studies oil tlic brain of the kiwi (Apterys sp.). (RI:niuscript.)
-
____
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presence, neocortex, mammallian, apteryx, evidence, additional, corte, vascularity, homologue, specimen, cerebral
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