On the Sensory Innervation of the Outer Genitals in Male Goat

Abstract

The sensory nerve supply of the urethra of goat is naturally poorer than in the higher mammals, including man, dog and cat, especially so in the pars cavernosa urethrae. In this part, the number of sensory fibres is very small and their terminal mode could not be elucidated as distinctly as desired, the excellent impregnation method I used notwithstanding. It was found, however, that some small-sized genital nerve bodies Type I and Type II were present in many places in the tunica albuginea of the corpora cavernosa, besides some simple branched terminations.The pars praeprostatica urethrae is better supplied with sensory nerves than the pars cavernosa above. The sensory terminations are, however, only very simple ones formed subepithelially or more rarely intraepithelially, comprising unbranched and simple branched terminations originating in medium-sized fibres.The pars muscularis urethrae is the best provided with sensory fibres and their terminations of all the parts of the goat's urethra. The terminations found here comprise a number of complex-typed ones, such as complex branched terminations and corpuscular terminations. It was of deep interest that capsulated genital nerve bodies Type I and Type II, never to be found in the urethra of dog or cat, could be observed in the m. urethralis of striated nature of goat, and that in large size and complex form. Often the Type II bodies were found to contain branched inner bulb with a terminal fibre per branch, in a common connective tissue capsule.The submucosa and the propria of the pars muscularis urethrae, corresponding the pars prostatica of the human urethra, contain nerve plexus containing thick sensory fibres, which mostly end in branched terminations, but besides glomerular terminations of non-capsulated type composed of terminal fibres showing frequent change in size and containing numerous cell nuclei are not rare either.Branched terminations are found in a considerable number beneath or within the epithelium of this part. The subepithelial terminations comprise unbranched, simple branched and complex branched ones, very often spreading over a large terminal area and having terminal fibres showing more or less marked or sometimes no change in size. The intraepithelial branched terminations are also formed in a rather complex manner. Their terminal fibres usually show little change in size and only very rarely reach the superficial layer of the epithelium.