Anat. Labor. of Prof. H. SETO, Tohoku University, Sendai.

Anat. Labor. of Prof. H. SETO, Tohoku University, Sendai.

Histology of Clitoris in Dog and its Innervation,

Especially Sensory Innervation.

犬陰核の組織学及び其神経特に知覚神経分布.

Morio KATO 加藤盛雄.

(Received June 12, 1955.)

The histological study on the innervation, especially the sensory inner-

vation of the external genital organs was taken up of old by KOLLIKER,

KRAUSE, RETZIUS, SCLAVNOS, DOGIEL, FERRARINI, SFAMENI,WORTHMANN, MULLER and DAHL, GELLER, MABUCHI, OHMORI,

TELLO and MATSUDA, and has been recently much furthered by mycolleagues in this laboratory-SETO, IKUI, K. YAMADA, SHIMIZU and

ENDO,-so that the fine structure of the sensory terminations in this

part has been very much elucidated. What has particularly interestedme has been the finding of comparative anatomical study that the sensory

terminations in the external genitals of different animals (ENDO, SHI-

MIZU) show rather widely varied peculiarities from those in man (K.YAMADA, IKUI et al.). In consideration of such peculiarities, I have

tried to investigate the hitherto little studied innervation of dog clitorisand to study its sensory terminations in comparison with those in man

and other animals.The materials of my study were taken from the external genitals of

three bitches. These were fixed for a long time in 10% neutral formol,

cut into series of transverse frozen sections and stained with SETO's

silver impregnation, and the series of numerous beautiful tissue prepara-tions thus obtained were minutely examined under a microscope. The

results obtained are reported in the following.

Individual Views.

SCHMALTZ (1910) has written in details on the anatomy and histo-

logy of the canine clitoris and ELLENBERGER and TRAUTMANN

have endorsed his findings, but since I have arrived at a rather largenumber of observations discrepant of his, I will speak upon the micro-

scopic anatomy of the part before entering upon the description of its

innervation. Anyhow, inasmuch as a description of the innervation ofa part without an adequate delineation of its histology is apt to become

a vapid and futile reading, it is of course imperative to preface a studyon the innervation with a description of the histology of the subject

22 M. KATO:

part which is very closely related with the former, especially with its

sensory innervation.

The corpus clitoris of dog is elongated along the median line of the

lower part of the sinus urogenitalis in the cranio caudal direction in the

form of a spindle 1.5-2cm in breadth in its cross section in the cranial

part and is bent in a gentle arch ventrally, as SCHMALTZ has remarked

(Fig. 1). But. as we go more caudal, its breadth gradually decreases

while its height increases somewhat and the middle of the ventral line

begins to project, so that it comes to take the form of a triangle with

its base line toward the dorsal side. According to SCHMALTZ, its caudalend is formed in a blunt point, but I found that it ends in a very pecu-

liar form, as detailed below.It is very interesting that this corpus clitoris is composed of fat

tissue, as SCHMALTZ, ELLENBERGER and others have pointed out

(Fig. 1). The connective tissue septum that is usually in formation alongthe median line is very poorly developed or altogether lacking in dogclitoris. The corpus is covered by a tunica albuginea composed of strongcollagenous connective tissue, as in man, but whereas it is composed of

two layers in man, in dog it consists of one circular layer only, poorlydeveloped on the dorsal and the ventral sides but rather well developed

on the lateral sides. A part, of the smooth muscle fibres running circu-

larly along the periphery of the sinus urogenitalis is found to wanderinto the surroundings of the tunica on its dorsal side. Near the median

line on the ventral surface of the corpus clitoris are found aa., vv. and

Fig. 1. Cranial part of corpus clitoridis of a dog. Cross section. Tunicaalbuginea (t) surrounding the fat tissue of corpus is well developed

ventrolaterally. a, v and n a. dorsalis clitoridis, v. dorsalis clitoridisand n. dorsalis clitoridis respectively. SETO's impregnation. Photo ×10.

Histology of Clitoris in Dog and its Innervation, etc. 23

nn. dorsales clitoridis, which gradually deviate to the lateral as the apex

of the corpus is approached. According to SCHMALTZ this corpus ends

abruptly in a blunt form beneath his so-called corpus cavernosum glandis,but in my study, I found that it enters the underdescribed clitoris, gra-

dually losing in size, becomes a dense mass of connective tissue cells

instead of the fat tissue as the glans clitoridis is approached, showingan ostensible cartilagenous hardness (Figs. 5, 4 and 3), and goes on dimi-

nishing in size till it tapers off near the caudal end of the glans clito-

ridis.

Fig. 2. Cross section of cranial part of clitoris of a dog. c

corpus clitoridis of fat tissue; v corpus cavernosum glandis;

p praeputium clitoridis composed of mucous folds; f fossaclitoridis; u sinus urogenitalis. Same staining. Photo ×10.

Fig. 3. Cross section of glans clitoridis of a dog. In the rightside, mucous membrane of the praeputium (p) is yet seen; ccorpus clitoridis composed of connective tissue; f fossa clito-

ridis; u sinus urogenitalis. Same staining. Photo ×10.

24 M. KATO:

The top of the sinus urogenitalis of dog opens into the SCHMALTZ's

so called fossa clitoridis formed by a depression of the vulva. This fossaextends as far as the radical part of the clitoris and ends blindly.

Complex folds of mucous membrane are formed in the blind bottom (Figs.

2 and 3). In short, the clitoris of dog is formed by a protrusion of the

Fig. 4. Cross section of glans clitoridis of a dog. c corpus clitoridis of

connective tissue; u sinus urogenitalis; f fossa clitoridis. Same staining.

Photo ×22.

Fig. 5. Clitoris of a dog covered with the mucous folds of fossa

clitoridis. Cross section. c corpus clitoridis composed of connective

tissue; n nerve bundles of n. dorsalis clitoridis; p propria provided

with many smooth muscle fibres; g epithelium of glans clitoridis.

Same staining. Photo ×22.


ventral wall of the sinus urogenitalis into the fossa clitoridis, its sagittal

section recalling that of a finger. The glans clitoridis contains in itthe cartilaginous tissue of the corpus clitoridis corresponding to the end-

phalanx of the finger. This observation is not in complete agreementwith that of SCHMALTZ, who asserts that the clitoris of dog consistsof a cavernous body extending from the bluntly ending apex of the corpus

clitoridis covered with a connective tissue capsule.

According to SCHMALTZ again, the cavernous body is covered byan extension of the mucous membrane of the fossa clitoridis, which hecalls the praeputium viscerale and the mucosa on the other or the opposite

side of the fossa the praeputium parietale. He says also that the prae-

putium viscerale is composed of a non-cornified cutaneous epithelium andthe connective tissue layer containing irregularly arranged papillae be-

neath it, but my study showed a very dissimilar picture, apparentlybetraying the utter looseness of SCHMALTZ's observations. As described

above, the dog clitoris is a finger-shaped formation hanging down from

the bottom of the sinus urogenitalis. Its glans is tomato formed in itscross-section (Fig. 4) with a quite smooth epithelial surface. The radical

part of the clitoris adjacent to the glans on its cranial side (Fig. 2) iscovered with a mucous membrane rich in folds so that its surface appears

very uneven. The epithelium covering the glans clitoridis is quite diffe-

rent from that on the radical part of the clitoris, consisting of a 6-7

rowed thin non cornified flat stratified epithelium, much as in the glansclitoridis of man and other mammals. No such papillar formation as

described by SCHMALTZ has been found beneath this epithelium, sothat the inner surface of the epithelium is even and smooth and is

bounded off from a propria very rich in cells through a basal mambrane

of considerable thickness. SCHMALTZ, however, has assumed the mucousmembrane lining the glans clitoridis to be identical with that covering

the radical part of the clitoris in structure, completely failing to notice

what I have given in the above. From the above findings of mine, itnaturally follows that it is quite out of the question to call the mucous

membrane of the glans clitoris etc. the praeputium viscerale etc., accor-ding to SCHMALTZ's proposition.

The epithelium of the much folded mucous membrane of the radical

part of the clitoris (Fig. 2), which SCHMALTZ has identified with thatof the glans clitoridis, is an extension of the epithelium lining the fossaclitoridis proper and consists in a very thick stratified epithelium con-

taining very large cells seemingly rich in glycogen. The mucous mem-

brane lined with this epithelium represents the inner lamella of the

praeputium clitoridis and the SCHMALTZ's so-called praeputium parietaleshould belong to this inner lamella too. The epithelium of the human

26 M. KATO:

praeputium, both in its inner and outer lamellae, is found to consist incornified skin epidermis, but the inner lamella of the praeputium penisof a male dog is lined with a mucosal epithelium (SHIMIZU). Conse-

quently, it is no wonder that the inner lamella of the praeputium clito-ridis of a female dog should consists of a mucous membrane. Into thisepithelium, well-developed papillae are frequently found formed out ofthe propria.

It is of deep interest that in a transverse section of the clitoris ina deeper part of the fossa clitoridis, a cavernous body is found in for-mation along both sides of the corpus clitoridis consisting of fat tissueand about 5mm in length of the base line. This formation of courseconstitutes the basal part of the corpus cavernosum glandis. The sub-epithelial layer lining the surface of this cavernous body, that is, thepropria in this part, is full of small vessels and capillaries as well assmooth muscle fibres running cross-cross among them, and contains nu-merous connective tissue cells, so that it presents a peculiar figure ofseeming toughness. When we proceed along the corpus clitoridis till itsbase line is shortened to the dimension of ca. 4mm, the formation ofthe cavernous body becomes further intensified, its two parts on bothsides of the median line uniting in one. When the corpus clitoridis isreduced in size to have the base line only 2mm long, the corpus caver-nosum reaches the maximum extension, measuring ca. 3mm in breadthand ca. 1.5mm in height. (Fig. 2). The development of the propria withits peculiar structure of mucous folds surrounding it becomes also furtheraccentuated. On the level where the breadth of the corpus clitoridis isfurther reduced to about 1mm, the development of the corpus caver-nosum glandis turns to decline, while that of the propria of peculiarstructure encircling the cavernous body from the lower and the lateralsides becomes more and more remarkable.

When the point where the fat tissue of the corpus clitoridis is super-seded by a dense mass of connective tissue cells is reached, the corpuscavernosum finally vanishes entirely (Figs. 5 and 6). In its stead, the

propria filled with smooth muscle fibres becomes even much better deve-loped. Even in this part, the surface of the clitoris is covered by mucousfolds. When the breadth of the connective tissue corpus clitoridis runsdown to a mere 0.3mm, the glans clitoridis at last makes appearance,as may be immediately perceived from the structure of the surface epi-thelium (Fig. 4). Here, the space between the epithelium and the corpusclitoridis consisting only of hard connective tissue is nearly filled up bythe propria full of a special tissue rich in smooth muscle fibres. The

peripheral part of the corpus clitoridis, however, is composed of a con-nective tissue free from smooth muscle fibres and contains many nerve


bundles of the n. dorsalis clitoridis. On the level where the breadth ofthe corpus clitoridis is further diminished to 0.15mm, the smooth musclefibres in the propria of this part nearly go out and their place is taken

by a dense connective tissue rich in small blood vessels (Fig. 7). The

tunice propria of such a structure continues in existence down to theforemost end of the glans clitoridis.

The above findings may be summarized as follows. The corpus clito -

Fig. 6. Large magnification of Fig. 5. Corpus clitoridis of connec-

tive tissue and nerve bundles of n. dorsalis clitoridis are shown

very distinctly; a a. dorsalis clitoridis. Same staining. Photo ×60.

Fig. 7. Head part of glasns clitoridis of a dog. Cross section. There isseen a fossula (f) opened in the epithelial surface; u sinus urogenitalis;

s sulcus coronarius glandis clitoridis. Same staining. Photo ×22.

28 M. KATO:

ridis elongated along the median line of the ventral wall of the sinus

urogenitalis in a cranio-caudal direction is composed of fat tissue, whichloses in size gradually as in the caudal part, the glans clitoridis is ap-

proached and finally is replaced by a dense group of connective tissuecells showing the apparent hardness of a cartilage. This again tapers offtill it vanishes entirely near the caudal end of the glans clitoridis. The

clitoris capped with its glans hangs down from the ventral wall of theforemost, end of the sinus urogenitalis toward the blind-sac fossa clitori-dis, containing a corpus clitoridis in it, and is shaped like a finger

extended craniocaudally. In a sagittal section, the corpus clitoridis ofconnective tissue may be likened to the end phalanx and the glans clito-

ridis to the finger-ball. The radical part of the clitoris is covered byfolds of the mucous membrane of the fossa clitoridis and the corpus

cavernosum glandis is formed only in the limited space covered by thesefolds (Fig. 8).

The clitoris of dog shows the above histological structure ascertained

in my study, and the accuracy of my description may be well understoodwhen you read the following description of the innervation, especially,

the sensory innervation, of this part. Firstly, we find in the cranial

end part of the corpus clitoridis the n. dorsalis clitoridis consisting ofseveral nerve bundles covered by connective tissue capsules rich in fatty

tissue running along the lateral side of the a. et v. dorsales clitoridisextending on the lateral sides of the median line of the ventral side of

the corpus (Fig. 1). These nerves gradually deviate laterally togetherwith blood vessels, when we go forewards along the corpus, sending out

Fig. 8. Schema of the sagittal section of clitoris and corpus clitoridisof a dog.


some small branches into the adjacent tissues, especially into the tunica

albuginea surrounding the corpus, in the course.

When the part where the corpus clitoridis is covered by the mucous

folds of the fossa clitoridis, or the radical part of the clitoris is reached,the nerve bundles that have been displaced to the lateral of the corpus

clitoridis become ramified into a larger number of branches (Fig. 2), a

part of which sends off minute branches into the corpus cavernosum

glandis that makes appearance on the ventral side of the corpus and theother part into the special propria of the praeputium. On a further fore-

ward level, where the fat tissue body of the corpus is replaced by aspecific connective tissue body, the nerve bundles of the right and left

nn. dorsales clitoridis subdivide into very numerous bundles, which diffuseas far as into the ventral side of the corpus clitoridis and send out small

nerve branches into the propria rich in smooth muscle fibres in this

part. In the glans clitoridis, the nn. dorsales clitoridis near their termi-nations, dissolving out into numberless fine nerve branches, which sendoff many branches into the propria rich in smooth muscle fibres as well

as into the propria free from smooth muscle fibres in the foremost part.

The n. dorsalis clitoridis originating in the n. pudendalis is composed

mainly of thick medullated sensory fibres with a small number of un-

medullated vegetative fibres intermingling. Since the corpus clitoridis isnot formed by cavernae but of a fat tissue, no vegetative plexus corres-

ponding to the plexus corporis cavernosi derived from the n. hypogastricusis found herein. The vegetative nerve plexus surrounding the a. et v.dorsales clitoridis are rather well developed. Now, in the cranial part of

the clitoris there is indeed a small-scaled corpus cavernosum glandis, andthe origin of the vegetative fibres supplied to it must be sought in these

perivascular plexus and the vegetative fibres found in the n. dorsalisclitoridis.

Of the sensory terminations of the n. dorsalis clitoridis, we are firstreminded of the PACINIAN bodies, for according to the detailed descrip-tion by YAMADA, PACINIAN bodies are frequently found in the course

of the n. dorsalis clitoridis in human clitoris. But to my surprise, I

found nowhere in the course of the n. dorsalis clitoridis of dog such acorpuscle in existence. SHIMIZU also failed in finding PACINIAN bodiesalong the n. dorsalis penis in the top part of dog penis, but in the deep

connective tissue layer of its praeputium he succeeded in finding smallPACINIAN bodies in frequent formation. Thus I was led to expect the

existence of such bodies in the praeputium clitoridis and searched for

them, but to the last I could not encounter any such a body here either,though owing to the extensiveness of the field of search, I am notutterly satisfied with the thoroughness of my search.

30 M. KATO:

There are found genital nerve bodies of Type III (YAMADA) in thetunica albuginea of human clitoris, especially between the outer and

the inner layers of the praeputium, and I suspected of its existence ofsome sensory terminations corresponding to the type in the tunica albu-

ginea of the corpus clitoridis of dog. In fact, I succeeded in actuallyfinding a comparatively large number of special sensory terminations in

the tunica albuginea, especially, on its ventro-lateral sides. In such atermination, a medullated sensory fibre from a small branch of the n.

dorsalis clitoridis running into the connective lamella of tunica albuginea,after losing its myelin sheath in most cases, enters the terminal territory

rich in special nuclei and spindle shaped or elliptoid in form, and termi-

nates, in a rather complex ramification (Fig. 9). Such a termination maybe called a noncapsulated branched termination, and corresponds to the

genital nerve body Type III in man.

When the n. dorsalis clitoridis proceeds to the part where the corpus

clitoridis is covered by the mucous folds of the fossa clitoridis, its rami-

fication becomes even more complicated, some branches running into the

mucous membrane of the fossa clitoridis and forming their terminations

in the propria beneath the thick stratified flat epithelium. These termi-

nations are always branched ones, and are much better developed in the

praeputium surrounding the cranial part of the clitoris than in the prae-

putium on the opposite side. Similar branched terminations are also

formed in the propria of the glans clitoridis, on which I will speak in

the next paragraph,

The nerve bundles of the n. dorsalis clitoridis run further into the

glans clitoridis, but no sensory nerve fibre is found to part from it

during the course to run into the corpus cavernosum glandis. Around

Fig. 9. A genital nerve body Type III found in the tunica albuginea in the

cranial part of corpus clitoridis of a dog. Details in the text. Same staining.×180, reduced to 2/3.


the corpus clitoridis of connective tissue of cartilaginous hardness, espe-

cially in the connective tissue on its ventral and lateral sides, we findvery numerous nerve bundles formed by ramification. In the cranial part

of the glans clitoridis, these bundles penetrate through the periproprial

layer rich in smooth muscle fibres into the subepithelial propria free fromsmooth muscle fibres to end there in most cases. In the lower end part

of the glans clitoridis the periproprial layer also becomes almost free of

smooth muscle fibres, being composed of a connective tissue layer similarto that in the propria, but sensory terminations are found chiefly formed

in the subepithelial layer here also.

The terminations formed in such propria include unbranched and

branched terminations. A medullated fibre, after losing its myelin sheath,

running mostly in a peculiar winding course showing perceptible change

in size, in an unbranched termination, ends in sharp or blunt point, orsometimes in an end knob or end brush (Fig. 10). Scarcely any of such

end fibres was found to run further up into the epithelium to becomean intraepithelial fibre.

Various forms of branched terminations are found to exist, namely,

1. Simple branched terminations: Very simple terminations formed of

2-3 branches. 2. Complex branched terminations: As shown in Fig. 11,

a single thick sensory fibre branches out into many rami, which run

very peculiar winding courses while undergoing frequent changes in size

and end in sharp points in an utterly irregular terminal arrangement.

3. Glomerular terminations: Either simple or complex in form. In a

simple glomerular termination, 1-2 thick sensory fibres make simple

Fig. 10. An unbranched sensory termination formed sub-

epithelially, showing a specific variety of thickness, running

a wavy course and passing over into a small end brush. Glans

clitoridis of a dog. Same staining. ×300.

32 M. KATO:

ramifications, each terminal branch ending in a simple glomerular ar-rangement, as shown in Fig. 12. In a complex one, the glomerular for-

mation of the nerve branches is considerably more complex. The termi-

nation located in the upper side of Fig. 13 belongs to this type, whichshows the interesting formation of one medullated fibre bifurcating into

two main branches, of which the one ends in a complex glomerulartermination while the other passes over into a branched termination. In

some cases, the branches of a glomerular ending show very distinct

neuro-fibrillar distensions in their running courses, and sometimes theminute branches undergo mutual anastomosis (Fig. 14). It is of interest

Fig. 11. A complex branched termination (b) formed sub-

epithelially. Glans clitoridis of a dog. Same staing. ×400.

Fig. 12. A simple glomerular termination originated in 2 thick

sensory fibres formed subepithelially. Clans clitoridis of a dog,

Same staining. ×300, reduced to 3/4.


that the glomerular terminations generally contain round special nuclei

much better staining than those in the connective tissue cells (Fig. 14).

Beside the above, some capsulated corpuscular bodies are also foundin the canine clitoris, especially in its glans. This type of terminations

is found also in the propria, but very rarely adjacent to the epithelium,being generally formed at a distance from it. Most of these are formed

Fig. 13. A non-capsulated glomerular termination (g) anda complex branched termination (b) originated in the samesingle thick sensory fibre formed subepithelially. Same

staining. ×300, reduced to 2/3.

Fig. 14. A non-capsulated glomerular termination pro-

vided with fibrillar expansions here and there found

beneath the epitheliaum of glans clitoridis of a dog.

Details in the text. Same staining. ×480, reduced to

2/3.

34 M. KATO:

among or in the vicinity of the nerve bundles spread around the corpus

clitoridis.

These end bodies belong in their fine structure to the genital nerve

bodies Type I and II. The end body Type I is, as exemplified in Fig.

15, generally oval formed and is covered by a conspicuous connective

tissue capsule, containing very numerous special nuclei in its inner bulb.

The 2-3 medullated fibres ending in such a termination, after losing

their myelin sheaths, run into the body through one of the poles and

ramify into many terminal branches, which end in a very complex glo-

merular arrangement filling up the inner bulb. The number of the

special nuclei found in a genital nerve body Type I in dog is incom-

parably larger than that in man, a finding similar to that by SHIMIZU

obtained with the genital nerve bodies Type I in dog glans penis. He

says that this type of terminations is found only in a limited number

there, and in my sections of the glans clitoridis of dog also the number

of the Type I bodies was much smaller than that of the genital bodies

Type II described below.

The genital nerve bodies Type II are capsulated bodies of marked

formation. These are generally oblong in form, but sometimes are shaped

in elliptoids. In their inner bulbs, special nuclei are founds in a smaller

number than those in the bodies Type I but far more numerous than

those in human genital nerve bodies Type II. In such a body, 1-2 thick

medullated fibres, after losing their myelin sheaths, run into the body

from one of its poles, send out more or less numerous branches, which

run very irregular courses chiefly in the central part, of the inner bulb,

Fig. 15. A genital nerve body Type I found in the propria of

glans clitoridis of a dog. Details in the text. Same staining.×300, reduced to 4/5.


often undergoing changes in size, and end generally in sharp points

(Fig. 16). Thus, in this type of termination, a large part, especially in

the periphery, of the inner bulb is free of nerve fibres and the nerve

ending takes the form of a branched termination.

The corpuscular termination shown in Fig. 17 probably belongs to

the genital nerve body Type II, but here, the special nuclei in the inner

bulb are aggregated in the central part of the body, its peripheral sub-

capsular zone being free of nuclei and appearing transparent. The single

Fig. 16. Two oblonged genital nerve bodies Type II found

subepithelially. Glans clitoridis of a dog. Details in the

text. Same staining. ×300, reduced to 2/3.

Fig. 17. A genital nerve body Type II very similar to a

RUFFINI's body found in the propria of glans clitoridis of a

dog. Same staining. ×300, reduced to 3/4.

36 M. KATO:

nerve fibre running into this corpuscle forms a very simple branched

termination composed of a few terminal branches. The terminal branches

at the tips all end in small neuro-fibrillar distribitions. The abovefinding reminds us of the so-called RUFFINI's end bodies found by

SHIMODA around the knee-joints of human embryos recently. As theseend bodies, however, have been found in the clitoris, a part of the

external genitals, they must be locked upon to have the same function

relating with sexual sensation as the genital nerve bodies. Therefore, Ibelieve they should be deemed to belong to the genital nerve bodies Type

II.

Summary.

The corpus clitoridis of dog extends in a cranio caudal direction along

the median line of the lower part of the sinus urogenitalis, gradually

losing size toward the caudal side, and ends in the glans clitoridis. It

is surrounded by a tunica albuginea consisting of one circular layer.

This corpus is made up of fat tissue, which is taken place by a mass of

connective tissue cells of cartilaginous hardness in the part nearer to the

glans clitoridis.The fossa clitoridis of blind-sac form, into which the sinus urogeni-

talis opens, extends down to the radical part of the clitoris and forms

mucous folds there. In other words, the canine clitoris is a formation

hanging down from the ventral wall of the sinus urogenitalis toward the

fossa clitoridis, forming the glans clitoridis in the caudal and the radix

clitoridis in the cranial part. A sagittal section of it reminds that of a

finger, the corpus clitoridis of connective tissue being like the end

phalanx and the glans clitoridis like a finger-ball.

The cross-section of the glans clitoridis is tomato-shaped and is lined

with a thin non-cornified stratified flat epithelium, which is free from

papillae growing out of the propria. The radical part, however, is coveredwith a very thick stratifified epithelium containing very large cells rich

in glycogen, into which well developed papillae grow from the propria.

That is, the radical part is covered by an extension of the mucous mem-

brane of the fossa clitoridis proper, so that this mucous membrane may

be taken to represent a part of the inner lamella of the praeputium.

A corpus cavernosum glandis is found in formation only in the

radical part of the clitoris. The propria around this body is very rich

in smooth muscle fibres, a condition continuing down to the middle part

of the glans clitoridis. In the part of the glans more caudal to that,

smooth muscle fibres are entirely absent, the propria consisting only of

a connective tissue layer rich in cells.

The n. dorsalis clitoridis consisting of several nerve bundles runs along


the ventral side of the corpus clitoridis in its cranial part but in the

more caudal parts they are reoriented more to the lateral. They send out

small branches into the tunica albuginea around the corpus in their

courses. This nerve subdivides into more numerous rami in the radicral

part of the clitoris, which send out minuter branches into the propria ofthe praeputium. In the part where the fat tissue of the corpus clitoridis

is replaced by connective tissue, nn. dorsales clitoridis dexter et sinister

become further ramified into more numerous bundles and extend as far

as to the ventral side of the corpus clitoridis, to send nerve branches

into the propria rich in smooth muscle fibres in this part. The nn. dorsales

clitoridis branch further into yet more numerous fine nerve bundles upon

entering the glans and give off many branches into the propria.

N. dorsalis clitoridis consists of many thick sensory fibres and a

small number of vegetative fibres. The vasa dorsalia clitoridis are sur-

rounded by well developed perivascular plexus of vegetative fibres. The

vegetative fibres entering the corpus cavernosum glandis originate in this

plexus and the vegetative fibres in n. dorsalis clitoridis.

No PACINIAN body was found formed in the course of the n.

dorsalis clitoridis of dog.

A rather large number of genital nerve bodies Type III originating

in the n. dorsalis clitoridis were found in the tunica albuginea of dog

corpus clitoridis. These are non-capsulated spindle-shaped or ellipsoid

bodies rich in special nuclei, with sensory fibres ending in branched

terminations in them.

The terminations of the sensory fibres from the n. dorsalis clitoridis

are formed in the subepithelial propria of the praeputium and glans

clitoridis. Their terminations are in most cases of the branched type.

Namely, a thick sensory fibre, after losing its myelin sheath, is divided

into a more or less large number of branches, which run peculiar winding

courses while undergoing changes in size and end in sharp or blunt points,

or in end knobs or end brushes. No fibres were found to pass over into

intraepithelial fibres.

The branched terminations include simple branched, complex bran-

ched and glomerular types. A glomerular termination contains dark-

staining round special nuclei and terminal branches in glomerular arrange-

ment.

It is of interest that sometimes a single sensory fibre is found to

branch out into 2-3 branches, which take upon severally different ter-

minal types.

Beside the above described sensory terminations, capsulated corpus-

cular bodies are also found in existence in the canine clitoris, especially

in its glans. Sometimes, these bodies are formed in the propria at a

38 M. KATO:

distance from the epithelium, but most of them are found among or near

the nerve bundles on the ventral side of the corpus clitoridis of connective

cells and may be divided into the Types I and II of genital nerve bodies.

The bodies Type I are oval in form, containing a surprisingly large

number of special nuclei in their inner bulbs and are supplied with

nerve fibres running into the inner bulbs and filling them up in complex

glomerular arrangement. These bodies are found only in a very limited

quantity.

The genital nerve bodies Type II are mostly elongated, but sometimes

also ellipsoid in form. The special nuclei in their inner bulbs are smaller

in number than those in Type I bodies. The nerve fibres here end in

branched terminations formed in the axial parts of the inner bulbs, the

subcapsular parts thereof remaining free of nerve fibres and looking

transparent.

Not rarely are capsulated end bodies found in the canine clitoris, in

which the special nuclei are aggregated at their axial regions, the sub-

capsular zone being nucleusless, and the nerve fibres supplying them

end in branched terminations in the nuclear part. These are very similar

to RUFFINI's end bodies in structure, but I would count them as a

subtype of the genital nerve bodies Type II.

内容自抄.

犬陰核は盲嚢の陰核窩に開口する尿性器洞の腹壁から陰核窩に垂れ下っ

た形成物で, 先端の著明な亀頭と基底部の粘膜皺襞所有の陰核根部とから

成る. 陰核体は尿性器洞の腹部に於て近位端から遠位端に向って徐々に細

くなり, 先端は亀頭内に終る. 本体は白膜で包まれ脂肪組織から成るが,

亀頭に近づくと固い結合織で置換される.

亀頭の横断像はトマト形を呈し, 上皮は薄い重層扁平上皮から成り, 固

有膜からの乳頭を有さない. 反之陰核根部の粘膜皺襞では大細胞から成る

甚だ厚い重層上皮と強力な乳頭形成が見られる.

亀頭海綿体の発達は劣勢で陰核根部内に形成されるに過ぎない. 其周囲

の固有膜は甚だ平滑筋線維に富む. 此状態は亀頭中間部まで続き, それよ

り先は結合織のみから成る.

数条の神経束から成る陰核背神経は陰核体の近位端では其腹側を走るが,

前進と共に徐々に外側方に変位する. 其走行途上分枝を白膜に出す. 背神

経は陰核根部に入ると更に多くの神経束に岐れ且つ固有膜に微細枝を出す.

陰核体が結合織で置換される部では両側の背神経の分岐は更に進み, 多

数の分枝は本体の腹側正中部に迄延びる. 亀頭内に来ると分岐は最高頂に


達し, 多数の微細枝は固有膜に送られる.

背神経は多数の知覚線維と小数の植物線維とから成る. 犬背神経では走

行途上形成さる可き Pacini 氏小体は認められない.

白膜内には陰部神経小体第III型が比較的多量に発見される. 之は特殊

核に富んだ非被膜性の紡錘状小体で, その中に分岐性知覚終末が形成され

る.

包皮及び亀頭の上皮下固有膜内には多数の特有な分岐性知覚終末が発見

される. 本終末の各分枝は太さの変化と特有な迂りとを示し, 尖鋭状, 鈍

状, 結節状又は刷子状に終る. 但し上皮内線維に移行するものは見られな

い. 尚お此分岐性終末は更に単純性, 複雑性及び糸毬状終末に分けられる.

糸毬状終末では濃染性の特殊核の含有を見る.

以上の知覚終末の外, 陰核特に亀頭内に有皮膜性小体様終末の存在を見

る. 之は陰部神経小体第I型と第II型から成り, 前者は卵円形で, 内棍は

驚く程多量の特殊核を含み, 神経線維は内棍を充満する甚だ複雑な糸毬状

配列をとって終る. 本型は少量に見られるに過ぎない. 後者は専ら長楕円

形, 特殊核は前者に於けるよりは少い. 神経線維は内棍中央部に分岐性終

末を作る. 従って内棍周辺帯は神経線維を含まず, 透明層を作る.

尚お特殊核が内棍中軸に集合し, 周囲の層は核を含まず透明帯をなし,

神経線維は専ら特殊核集合部に分岐性終末を作ることによって表わされる

有被膜性終末小体と稀ならず発見される. 之は所謂 Ruffini 氏小体を思わ

せるが, 余は存在場所を考慮して, 之をと陰部神経小体第II型に所属せ

しめた.

References.

Dogiel: Arch. mikr. Anat. 41 (1893). -Ellenberger u. Trautmann:

Histologie der Haussaugetiere. 5. Aufl. Berlin, P. Parey, 1921. -Endo: Arch.

hist. jap. 6 (1954). -Ferrarini: Anat. Anz. 29 (1906). -Geller: Zbl. Gynak.

46 (1922). -Hotta: Arch. hist. jap. 4 (1952). -Ikui: Tohoku Igaku Zassi.

(Jap.) 39 (1949). -Kolliker: Handbuch der Gewebelehre. III. Leipzig, W. Engel-

mann, 1902. -Krause: Z. rat. Med. 5 (1858), cited by Stohr. -Mabuchi:

Mitt. med. Fak. Tokyo. 31 (1924). -Matsuda: Kaibogaku Zassi, (Jap.) 8 (1935).-Muller u. Dahl: Dtsch. Arch. klin. Med. 107 (1912). -Ohmori: Z. Anat.

70 (1924). -Retzius: Internat. Mschr. Anat. u. Physiol. 7 (1890). -Schmaltz:

Ellenbergers Handbuch der vergleichenden mikroskopischen Anatomie der Haus-

tiere. II. Berlin, P. Parey, 1911. -Sclavnos: Ant. Anz. 9 (1894). -Seto:

Arb. Anat. Inst. Sendai. 22 (1939). -Sfameni: Arch. ital d. biol. 34 (1906),

cited by Ohmori. -Shimizu: Arch. hist. jap. 6 (1954). -Shimoda: Arch.

hist. jap. 9 (1955). -Stohr: Mikroskopische Anatomie des vegetativen Nerven-

40 M. KATO:

systems. Berlin, J. Springer, 1928. -Suga: Tohoku Igaku Zassi. (Jap.) 54

(1951). -Tello: Trav. Lab. Rech. Biol. Madrid. 28 (1932). -Yamada, K.:Tohoku J. exp. Med. 54 (1951). -Yamada, M.: Arch. hist. jap. 7 (1954). -

Worthmann: Arch. mikr. Anat. 68 (1906).

Anat. Labor. of Prof. H. SETO, Tohoku University, Sendai.

Documents

Transcript of Anat. Labor. of Prof. H. SETO, Tohoku University, Sendai.