The distribution of nerves supplying the testis, epididymis and accessory sex glands of Suncus murinus.

Chronic testicular pain remains an important challenge for urologists. Investigation of the innervation of male gonads thus becomes essential for deepening our understanding of their regulatory roles in male reproductive physiology and pathophysiology. Studies of testicular innervation are mainly limited to the intratesticular peptidergic nerves of the testis by immunohistochemical and acetylcholinesterase histochemical investigations in some animals. Little is known about the detailed, overall distribution in general experimental animal testis. In this study, the distribution of nerves supplying the testis, epididymis and accessory sex glands of Suncus murinus was investigated by whole mount immunohistochemistry staining using a neurofilament protein antibody. Testicular nerves arose through three routes: nerves deriving from the mesenteric and renal plexuses accompanied the testicular artery, entering into the testicular hilum through the superior ligament of the testis. The nerves originating from the hypogastric plexus then ran along the internal iliac artery, deferential artery, and passed through the mesoductus deferens or mesoepididymis, innervating the cauda and corpus of the epididymis, the vas deferens and the inferior pole of the testis. The third route arose from the pelvic plexus, distributed in the seminal vesicle and the prostate. The density of nerve fibers was higher in the cauda epididymidis than in the testis, and more abundant in the vas deferens. The different origins and distribution densities of testicular nerves in S. murinus may serve different neuronal regulatory functions, and, therefore, S. murinus may be an important model animal for understanding the different characteristics of testicular pain.