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Quantitative studies of the testicle. II. Pattern and total tubule length in the testicles of certain common mammals

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QUANTITATIVE STUDIES O F THE TESTICLE
11. PATTERN AND TOTAL TUBULE LENGTH IN THE TESTICLES O F
CERTAIN C O M M O N MAMMALS
K. 3’. BASCOM AKD H. L. OSTERUD
Medical College of Virginia
INTRODUCTIOK
Studies of the morphology of the testicle have been largely
qualitative in character. Quantitative data, however, exist
with reference to gross weight, tubule diameter, tubule
length, and cell counts. As examples may be mentioned the
work of Bouin and Ancel, Hatai, Jackson, Massaglia, Latimer, and Ressesen and Carlsoii, who have rocordecl gross
weights of the testicles of various animals. Siperstein, in
addition to gross weights, also gives the diameter of the
seminiferous tubules and diameter of nuclei of interstitial
cells. Moore, in a later paper on experimental cryptorcliidism, gives gross weights and tubule diameters. T.l.Tatson
records seasonal changes in testicular diameter in the green
finch. Riddle off’ers data on size and length relations in the
right and left testes of the pigeon. Rasmussen, in his study
of the seasonal changes in the marmot, employed cell counts
of interstitial cells and records percentage weights of the
testicles. Lengths of individual tubules were determined in
the mouse, rabbit, and dog by Curtis. Huber and Curtis,
writing on the seminiferous tubules in mammals, mention in
an incidental way some quantitative data as to tubule length.
Cunningham’s Nanual of Practical Anatomy, without citing
the source of information, makes the statement that the human testicle “~onsists of four to six hundred fine hairlike
, each of which is ahout 60 em. (two feet) long.”
tuhcs
169
160
I<. F . RASCOM AND H. 1,. OSTERUI)
To our knowledge, no quantitative method has been applied
to the measurement and comparison of total tubule length
of the seminiferous tubules in a series of laboratory ant1
domestic animals. I n this paper such a method and the results of its application are set forth.
MATERIALS APU’D METHODS
Total tubule lengths of single normal testicles were computed for the following species: albino mouse, albino rat,
Guinea pig, cat, Belgian hare, dog, man, pig, sheep, and bull.
T h c ~testicles were separated from the cpididymis and other
extraneous tissue and were weighed in the fresh condition
1wfor.e fixation. I n tlic case of certain representative testicles
of the bull and pig, the tunica albuginea was stripped off and
the mediastinum dissected out in the fresh condition and
w-ciglied separately from the rest of the testicle.
Bouiri’s fluid was used in general as the fixative, Zenker’s
fluid and 10 per cent formalin in a few cases. The testicles
of the mousc’, rat, Guinea pig, cat, hare, and dog were fixed
for a brief interval entire and then sliced with a razor for
further fixation. From the larger testicles blocks of tissue
were removed with a razor and fixed. Both celloidin and
paraffin were used for embedding, the former, to the greater
extent, proving also the more satisfactory. The combination
of stains most frequently used was hematoxylin-eosin.
The quantitative technique employed for determining total
tubule length may best be presented by following successive
steps in two typical examples.
E ~ a n a p l e 1. Hull iesticle X 3. Fresh weight, 274 grums
By the steps previously outlined it was determined that the tnnica
albuginea and mediastinum weighed 15.5 grams (5.6 per cent of the
total weight of this testicle). Hence tubules and interstitial t
weighed 258.5 grams.
Several representative fields in sections of this testicle were projected with an Edinger drawing apparatns and the tubules drawn
in outline. Then the relative amounts of tubules and interstitial
tissue present in these drawings were measured in two ways: by
QUANTITATIVE STU1)IES OF T H E TESTICLE
161
use of a polar planimeter and by the paper method already employed
by Baseom in estimating the amounts of interstitial tissue in testicles
of swine. In testicle X 3 the relative percentages of tubules and
interstitial tissue were, respectively, 83.9 per cent and 16.1 per cent.
Since, as already stated, tubules and interstitial tissue together
weighed 258.5 grams, according to the above percentages the testicle
was calculated to contain 216.88 grams of tubules. For all practical
purposes the specific gravity of fresh tissue may be taken as 1.0,
hence the 216.88 grams of tubules are assumed to be very nearly
equivalent to a volume of 216.88 cc. or 216,880 cu.mm.
By means of a microscope with eyepiece micrometer, the average
diameter of fifty seminiferous tubules was found to be 0.238 mm.
Using the formula rr2, the average cross-sectional area of the seminiferous tubules was calculated to be 0.0446 sq.mm. Dividing total
tubule volume in cubic millimeters (216,880) by cross-sectional area
in square millimeters (0.0446) gives the total tubule length of this
testicle in millimeters (4,862,000). This sum is more compactly expressed as 4862 meters or as 4.862 kilometers.
Eza.nzple 2. Guinea-pig testicle X .I2A. Fresh weight, 1.2423 gmms
In this case the tunica albuginca and mediastinurn could not conveiiient.ly be dissected away in the fresh condition. Representat.ive
transverse sections from different, parts of the testicle were prepared.
Ry means of the Edi.riger apparatus, a drawing was made from 'one
of these sections and, with the aid of the planimeter, the percentage
of mediastinum present was calculated (8.89 per cent). This was
assumed to be the percentage of mediastinum in this testicle.
The volume of tunica albuginea was det,ermined i n a different way.
Its thiclrness was measured with a n eyepiece micrometer and found
to average 0.031 mm. The Guinea-pig testicle approaches the spherica.1 form rather closely. Accordingly, testicle X 12 A was assumed t o
be a sphere having a volume of 1.2423 cc., or 1242.3 cu.mm., t.he
volume assumed to be equivalent to the weight of this testicle. The
volume of a sphere equals
&, hence a sphere of the above volume
has a radius of 6.668 mm. The thickness of the tunica albuginea
(0.031 mm.) subtracted from t.his ra.dius gives 6.637 mm. as t.he
radius of the smaller sphere, wit.h a volume of 1223.6 cu.mm., representing t.ubules and interstitial tissue and mediastinurn.
The percentage of mediastinum in t.his testicle, calculat.ed as shown
above, was 8.89 per cent, equivalent to 110.4 cu.mm. Hence t.he net
volume of t.ubules and int.erstit.ia1tissue becomes 1223.6 minus 110.4,
or 1113.2 cu.mm. Of this volume 91.83 per cent, or 1022.25 cu.mm.,
was seminiferous tubules, determined as in example 1. Average
t,ubule diameter was determined by micrometer measurement to be
-:.
162
K. F. BASCOM AND H. L. OSTERUD
0.244 mm. Employing the formula d,
the average cross-sectional
ar~lais 0.0467 sq.nirn. Dividing volmne of tnbules (1022.2,?) by
(.row-sectional area (0.0467) therefore gives 21,889 inin., o r 21.889
iiictcr-s as the total Inbule length in this testicle.
We believe these two examples sufficiently illustrate the
methods by which the results to be set forth in this paper
were obtained. Corrections have not been made and could
not easily be made f o r certain minor. errors, such as assuming
tlic (lninea-pig testicle to be pcrfectly spherical, assuming
the specific gravity of the testicle i o be 1.0, or assuming that
all elements of the testicle shrink equally under such technical treatment as we have employed, but we do not believe
that they substantially affect our result.'
Tlianks are due A h . IIermari Neltori for tec2mical assistance.
RESULTS
The iiumerical data obtained by the above methods are
summarized in table 1.
1)IBCTJSSlOA
la table 1 the column of gross weights of testicles sl~ows
great variation in weight in the cliEcrcnt species-from 0.0556
gram in the mouse to 367 grams in a boar. I n view of this
great ciisparity in testicular weights, it is interesting t o fiud
that the diameters of the tubules in the above-mentioned testicles are, respectively, 0.191 mm. and 0.223 mm.-a cliffcl*'All ctilculations as t o perceiiinge composition a r e based on the p1:ininwtrr
method for the sake of uniformity and because we believe it t o be more accurate
tliiin the piper method. We hare also found it t o be more rapid and less tedious.
Results obtained by applFing both methods to each of twenty-six testicles of
:~nimals of ten different species show a n :iver:rge discrepancy between the two
scts of resultx of 3.45 per cent, figures olitained with the planimeter metliotl
1)csing on tlic :ivcr:igc sliglitly Iiiglier t1i:in those woykerl out by tlie paper metlioil.
T n the first p:ipcr of this series (B:iscom, '2.5) no :illow:mce \\:IS m:ittr for
tunic1 :ilbugine:i and medi:istiiiuni in ciilcn1:tting the amounts of tubules :ind
i n t c w t i h l tissue m
i pig testicles. 1lel:itive peiwntnges of tubules and interstitial
I k s u e :ire not affected I)? this error, but :tbsolute weights of these clcinents as
gi\cn i t 1 that picper are :il,ont 8 per cent too large.
16.3
QUAKTITATIVE STUDIES OF THE TESTICLE
TABLE I
-
_.
.. .
Albino mouse
SL 1
M2
I
;Ii 3
Albino mt
1
It1
li 2
3*
1C SA
'
x
K 3B
K. 11
(;oillea pig
s 1IA
s 11B
s 12.1
s 1211
0 .chi56
0.0Mfi
0.0746
0.0477
0.0321
0.0641
0.191
0.191
0.2008
0.0286
0.0286
0.0316
1.67
1.82
2.03
1.2%
1.13
0 . m
1 .-"497
1.288.3
1 .0283
1.a584
0. !I834
0.2422
0.248
0.0458
0.2"48
1 .087.5
1.1414
0 .9031
0.1652
0.2494
0.2589
0.2654
23.1
20.3
10.55
2 2 , :3
21.i
16.3
I .ti4
1 .493
1.5074
I .0222
0.9794
1 .0:31
I .W3B
1.7160
0.197!)
0.2084
0.244
0.2391
0.2262
0.231 A
0. Y3i9
0 . ;imi
0 .titi'25
0.1 7%;
0.1806
1.8556
0.183;
0.07
1.67
1,2m
1 .1 (itE
1 . 1ti&
1,1846
1.9!E%5
S 13A
s 1311
s 20
Cat
s lA*
s 113"
0.8
0.94
Belgian 1i:irc
x in
2.307
0.1075
s I!)*
,
I
0 . 1193
0.0484
0 . 0 2 13
0.0487
0. aw
0.0533
0.0307
o.o:x39
().CCz(ji
0.0448
0.0402
0. ot2
0.0443
0.CMi4
I).0037
48.6
44.4
21.8!)
21.8
2,j.f i
24. r;
38.7
70.2
3L.2
I)0g
s "h
x 21i
ti.5
137. 8
167.7
12.21
244'3.7
6.0
I
218.0
M i .O
15.0
89.0
1 (it\ ,o
125.29
246. 18
3 1 64
63 1 2
10.2113
70.44
129.4s
1092
41 19
37.53
2lti.88
4862
4LMl
4814
:3::19
lti4
I<. F. BASCOM A N D H. L. OSTRKUI)
~ i i of
~ eonly 14.3 per cent. Rat testicle R 11 had a greater
tuhulc diameter (0.2654 mm.) than writs foiiiid in an>- other
t eslicle stutlicd, not excepting even those of thc hoar, bull, o r
ixm. The smallest a r e m g c tubnle diameter in the adult mas
found in the human testicle X 10 (0.1834 mm.). The maxiniiirn vnr*iatioii ill tixhnle diameter iii this series of testicles
is t l i e I 1 , i l l rouiitl iiumhers, 30 per cent. There is no direct
rclatjoilship hettvceii tubule diameter arid the size of the adult
ti~iimnlso far as our evidencv goes.
TABLE 2
i
fil'EU1r:s
...
.
.
. .~~
!
~
hIo11se ..................
Kilt
(adr1lt)
....
...
...
(.:at#( n c l t frill grow11) . . . .
t h o (:1dnlt) . . . . . . . . . . .
Hiire (i tiiiri:itii R:) . . . . . . .
'I )"Is_. . . . . . . . . . . . . . ., . . . . :
Iht
(iiniiiiit
< i n i ~ i c ~pig
n
31il I1
...................
1.
.
..........
1..
2T .2 -30.3
15.8 18.2
39.8
1 7 . 6 21 .!I
27.4-28. $5
31.4
1f i3 .0
22.9 "5.8
m.4
Pig. ....................
Sheep ($1 170, wdult) . . . . .
Shccp (M 135, (imos.). . .
46.2
Sht?qJ(M %!), 3 mos. j . ..
'I1I l l 1....................
Id. 1-23. i
14.tj l i . 2
2 . 6
iO.0
Thc average cross-sectional area of the lubnle in the rat
tcnticlc R 11 is 0.0553 sq.mm. and in the human testicle X 10
is 0.0263-in rouiitl iiumhers, a difereiice of 50 per cent.
r1.i he significance of tubule size may perliaps bc more easil~*
gi*aspetlwlitlri expressed as in table 2, column 1, in terms of
tlw nnml)cr of rncdors of tuhiile,s cqixivaleat t o 1 gram iii
weiglit or 1 cc. i u volume.
Kveri after allowance is made for tuiiica albugiiiea am1
metliastiinim, normal adult testicles vary in relative percent ages of tnhules and interstitial tissue. These variations in
the species studied arc summarized in table 3. In each case
165
QUANTITATIVE STUDIES OF THE TESTICLE
the percentage of interstitial tissue is therefore equal to 100
miniis the perccntage of tubules given in the table.
Table 3 consequently indicates numerically the differences
in pattern found in this series of normal adult testicles due
t o varyiiig amounts of interstitial tissue.
Total tubule lengths f o r the adult ariimals studied are summarized in round numbers in table 4.
Incidental data exist from which total tubule length in the
testicle of man and of the mouse may be calculated. Cunningham gives figures indicating a total tubule length in
the human testicle of 800 to 1200 feet. Our calculation, involving a different method, gives 249.7 meters, or 819 feet.
Guinea. pip I
Dog. . . . . . . .
1
M ~ I I R .~ .. . . . I
Hare. ......
,
Rat . . . . . . . .
Cat ........
Sheep . . . . . . .
Bull. . . . . . . . !
Alan ....... ’
Pig ........
8!). 8-97.0
92.2-94.2
88.9-90.3
89.0
88.5-89. f i
84.5-86.9
84.6
76.4-83.9
72.8
62.2-72.6
i
.............
2
Rat ................
20
(hinea pig. . . . . . . . . ,
40
Cat (not full grown)
25
Belginn hare . . . . . . .
70
Dog ...............
150
&Ian... . . . . . . . . . . . . I 260
Pig ................ 3 o o o ~ ~ - m
Sheep .............. 4000
Rull . . . . . . . . . . . . . . . 5000
Moiise
1
~
.
. ..
-.
...
Huber and Curtis state that the mouse testicle contains
sixteen tubules. One tubule was found to be 13 em. in length.
These figures imply a total tubule length for the mouse testicle of about 2 meters. Our figure, iridependently calculated,
is also about 2 meters. To this extent previous data secured
by methods entirely different from ours confirm our comput at i on s.
At first glance the disparity in total tubule length between
the larger and smaller mammals seems fairly incredible, but
a little arithmetic will reveal that actually the smaller animals have a greater length of tubules per unit of body weight
16li
I<. I,’. BRRCOM A N D H. L. OSTERUD
t l ~ do
n the larger ones. F o r example, in round numbers, a
molls(’ would h a r c iihoiit 1 meter of tubules per 10 grams of
I)ody weight, while a bull would have approximately 1 meter
of tnhnles per 100 grams of body weight. If the testicle made
up tho same percentage of body weight in the bull as it does
in the mouse, tho bull testicle u70dd have, instead of 5000
rncLtvix of tubules, upwards of‘ 300,000 meters. In this conion it is iiitevesting to refer oiice more to table 1 and
note that tho mouse has a tuhule diameter of almost 0.2 mm.,
\vIlilc. the bull has an average tubule dianieter only 16 pcr
cent greater (0.24 mm.). In other words, increased volume
of germinn1 fyitholium in larger tc*sticAlcs comes largely or
wholly from iiici-ease in tubiile lwgtli, not from increase iu
tiilnde diameter.
( ‘pi-tail1immature animals are marked in tnhle 1 witli ast(’i0isks. Rat K 3 was thirty-nine (lays old arid weighed 59..?
gixrns. His tcsticle \wiglit was approximately 25 pcr cent
t h a t of a iiormal atlnlt, but the total tubulc leiigtli of his tcsticlc was iilwut 50 per cent that of the adult.
]<;it K 2 \$rils sixty-six (lays oh1 N I I ~weighed 150 grams.
His testicolar weight anti t ul)iile length were almost those of
thr. aclult, although oiily i n the carlimt stages of sexual miit nrit y.
Rat R 1 was 190 clays old and weighed 304 grams, yet his
1chsticillar weight am1 total tu’lntle leiigth olily sIight1~-oxccwied tliosv of H 2, \\-1io w a s oiici-third his age a d 011c-11;iIf
liis 1)od:- w-eight.
Kclgiaii hart X 19 TWS less tl1a11 i i third ~ T O M - I ~ . His t(hbticular 1s-eight was ahout oiie-elerenth and his tuhule lc11gt11
two-fifths that of X 18, an iitlnlt of the> same spccics.
JI 399 1i7:is ii lamb, pcrlinps three months old. Its testiciil a r weight was ahout one-ele\-mitIi that of the atfult, hnt its
ir i l ) i i l ( l It~iigtlim o w t l i a i i oiic-fourth that of the atlillt.
Ji 13i w w ;I laml) akout six months old. Its tes:tic.111;11*
wt.ig-tit w i s ahout Iialf that of the adnlt, h t its tnbnle lellgtll
;it loiisf ( v l i i a l t o t1i:it (JI’
acliilt ,I1 I i O .
QUANTITATIVE STUDIES OF THE TESTICLE
167
These comparisons of immature with mature testicles lead
to the conclusioii that total tubule length is greater in proportion to testicular weight in the young than in the adult
testicle and that adult tubule length is probably attained in
the growing animal a considerable time before adult testicular weight and adult tubule diameter have been reached.
The factors which determine testicular pattern are tubule
diameter, relative amount of interstitial tissue, and amount of
tunica albuginea and mediastinum. These factors are individually variable. Tlie combined effect of their variability
upon testicular pattern may he expressed numerically as in
table 2, column 11,in terms of the number of meters of tubules
per gram of testicular weight. These data are obviously
secured by dividing the total tubule length of given testicles
in meters by their respective weights in grams. This column
illustrates the following points : similarity in pattern in tlie
adult testicles of certain species, differences in pattern in
the adult testicles of other species, a r i d changes in pattern
during growth in a given species.
BCMNAlIY AND COKCLUSIONS
1. A quantitative method is described for determining the
amounts of interstitial tissue and seminiferous tubules as
well as the total length of these tubules. Testicles from animals of the following specics wei’cl studied : albino mouse,
albino rat, Guinea pig, cat, Belgian hare, dog, man, pig, sheep,
and bull.
2. The gross weights of these testicles ranged from 0.0556
gram (albino mouse) to 367 grams (boar).
3. Adult tubule diameter had a maximum variation of only
0.1834 mm. (man) to 0.2654 mm. (albino rat).
4. Total tubule length in the adult varied from 1.67 meters
(albino mouse) to 6312 meters (hoar).
5. The small variation in tubule diameter in conjunctioii
mitli tlie tremendous differences in total tubule length indicate that space f o r increased volume of germinal epithelium
in the larger testicles is afforded largely and sometimes
1C58
Xi. %’. BASCOM Ah’D H. L. OSTERUD
wliolly by iiicrease iii total tubule lengtli, not b y increase in
t nhule diamet cr.
ti. In spite of the great total tubule length encountered iii
the larger species. the smaller animwls, such as the mouse
and rat, actually have a greater length of seminiferous tnbides per unit of body weight.
7. The pattern of a given testicle depends upoii the relative
arnooiits of tunica albuginea, mediastinurn, interstitial tissue,
aiitl tubules, ant1 upoii tuhule diameter. The combination of
these factors as they occur iri a given testicle may be iiumcrically expressed in terms of number of meters of tubules per
gram of total testicular weight. This slim varies with thtl
species studied as well RS with the state of development of
the individual (table 2, column 11).
8. Total tubule length is greater in proportion to total
testicular weight in the poung than in the adult.
9. Adult tubule length probably is attained in the growing
aiiimal a considerable time bef ore adult testicular weight and
adult tubule diameter have been reached.
QUANTlTATITrE STUDIES OF THE TESTICLE
169
BIBLIOGKAYII Y
BASCON,K. F. 1926 Qu:intitative studies of the testis. T. Some observations
on tlir ervptorcliid testes of sherp and swine. Anat. Rec., vol. 30.
RESSESEN,A. N., AND CABLSOX,H. A. 1923 Postnatal growth in weight of the
various orguns in the guinea pig. Am. Jour. Anat., vol. 31.
BOUIN AND ANCEI, 1903 Testicule des M:immifcres. Arch. de Zool. Exp. et
Gm., T. 1.
1904 Ulande interstitielle du testicule. Jour. de Phys. et de Path.
Gen., T. 6.
BREMER,J. L. 1911 Moiphology of the tubules of the liunian testis and epididymis. Am. Jour. Amit., vol. 11.
CURTIS, G . M. 1918 The morpl~ology of the mammalian seminiferous tubule.
Am. Jour. Anat., vol. 21.
HATAI, SHINKISHI1913 On the weights of the abdominal and thoracic viscera,
the sex glands, duetless glands, a n d the eyeballs of the albino rat
(ItIus norvegicus albiiius) according t o body weight. Am. Jour.
Anat., vol. la.
JACKSON,
C. M. 1913 Postnatal growth m d variability of the body and the
various organs in the albino rat. Am. Jour. Anat., vol. 15.
LATIMER,H. B. 1920 The weights of the viscera of the common frog. Anat.
Rrc., ~ o l .18.
1920 The weights of the viscera of the turtle. Anat. Roc., vol. 19.
MASSAGLIA,A. C. 1920 The internal secretion of the testis. Endocrinologp,
vol. 4.
IIUBER,
G. C., AND CURTIS, C . M. 1913 Thr morpl~ology of the seminiferous
tubules of mammalia. Anat. Rev., vol. 7.
MOORE,
C. R. 1924 Properties of the gonads iLS rontrollers of somatic an d
psychieal characteristics. VI. Testicular reactions in experimental
eryptorchidism. Am. Jour. Anat., vol. 34.
RASNUSSEN,
A. T. 1917 Seasonal changes in the interstitial cells of the testis
in the woodrhuck (Marmota monax). Am. Jour. Anat., vol. 22.
1918 C;yclic changes in the interstitial rells of the ovary and
testis in the woodchuck (Marmota rnonax). Endocrinology, vol. 2.
RIDDLE,OSCAR 1916 Size and length relations of the right an d left testicles of
pigeons in health and disease. Anat. Rec., vol. 11.
1918 Further observations on the relative size and form of the
right and left testes in pigeons in health an d disease as influenced by
hybridity. Anat. Rec., vol. 14.
ROBINSON, ARTHUR 1920 Cunningham’s manual of practical anatomy, 7th
edition. Vol. 2. Thorax and abdomen.
SIPERSTEIN,D. M. 1921 The effects of acute and chronic inanition upon the
development and structure of the testis in the albino rat. Anat. Rec.,
vol. 20.
WATSON,ALEXAKDER1919 A study of seasonal changes in avian testes. Jour.
of Phys., vol. 53.
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