On the Sensory Nerve Supply of the Female Outer Genitals in Flying-Squirrel

Abstract

The deep part of the sinus urogenitalis of flying-squirrel is surfaced with a 3-rowed cylindrical epithelium, but its portion between the projecting tip of the glans clitoridis and the outer orifice, about 6mm in length, is under a non-hornified stratified flat epithelium. The propria mucosae is of fibrous connective tissue.The corpus cavernosum clitoridis is similar in construction as the cropus cavernosum penis of male flying-squirrel. The glans clitoridis is covered by an epithelium in common with the inner plate of the praeputium, as the glans penis of male flying-squirrel and the glans clitoridis of man and some other animals in fetal stage.The corpus cavernosum clitoridis runs up to the apex of the glans clitoridis; its stout connective tissue in the proximal portion turns into a bony tissue in the more distal portion, which again in the distalmost end portion is replaced by a chondroid tissue. The space between the common epithelium and the cavernous body is filled up by a connective tissue rich in fibrocytes. The common epithelium is lined with the propria of loose connective tissue of the inner plate of the praeputium.The sensory fibres supplied to the clitoris are derived from the n. dorsalis clitoridis. This nerve runs forward along the ventral side of the corpus cavernosum clitoridis, while sending out a few fine branches into the tunica albuginea of the cavernous body and to the ventral side of sinus urogenitalis.The dorsal nerve does not form PACINIan bodies anywhere on its course in flying-squirrel. The tunica albuginea contains a small number only of unbranched and simple branched terminations.The sensory fibres coming into the mucous membrane of the sinus urogenitalis covered by the cylindrical epithelium originate in the n. perinealis as well as in the dorsal nerve, and are much smaller in number than those entering the cavernous part of the urethra of male flying-squirrel. No such corpuscular terminations as found in dog are found here, only unbranched and simple branched terminations being found formed sub- and intraepithelially. The terminal fibres of these terminations not rarely consist in thick fibres running winding courses while showing frequent change in size.Most of the dorsal nerve bundles run into the glans clitoridis but not a few proceed into the inner plate of the praeputium. The nerve fibres, upon coming into the glans clitoridis, spread out toward the common epithelium. Their terminations are often formed around the cavernous body, but most frequently beneath the common epithelium. Some of the fibres form intraepithelial terminations in the common epithelium.The sensory terminations characteristic to this part are the specific branched terminations, specific genital nerve bodies and the intraepithelial fibres in the common epithelium.The specific branched terminations are characterized by the frequent change in size and the irregular winding courses of their terminal fibres and the mutual anastomosis between them. The other non-specific branched terminations have fine terminal fibres showing little change in size and winding courses and are found around the cavernous body and subepithelially.The genital nerve bodies are always capsulated and may be classified into Type I and Type II, the former containing glomerular terminations and the latter branched terminations in their inner bulb. The Type I bodies comprise two subtypes; the one with rather thick terminal fibres showing perceptible change in size and the other with very fine terminal fibres in the inner bulb. Some of the genital bodies Type II are single bodies, but some are compound bodies with branched bodies. It is of interest that some of the later oftten enough encased in a stout common capsule. The branches of the compound bodies are mostly crowded together, so that it is very difficult sometimes to define their outline.