NEURONAL INPUT FROM THE INFERIOR MESENTERIC GANGLION (IMG) AFFECTS SPERM TRANSPORT WITHIN THE RAT CAUDA EPIDIDYMIS

Sympathetic nerves emanating from the inferior mesenteric ganglion (IM G) innervate the mammalian epididymis and vas deferens. We have report ed previously that surgical removal of the rat IMG results in excessiv e accumulation of spermatozoa within the cauda epididymis. The objecti ve of the present study was to determine whether sperm accumulation fo llowing IMG removal was due to a denervation-induced change in the rat e of sperm transport within the cauda epididymis. In these studies epi didymal sperm numbers were counted and used as a measure of sperm tran sport within the epididymis. In order to examine sperm transport withi n the cauda epididymis specifically, efferent duct ligation (EDL) was used to prevent further entry of testicular spermatozoa into the epidi dymis. Rats were divided into four treatment groups: sham-operated con trol, EDL alone for 7 days (EDL+7), EDL alone for 14 days (EDL+14), or EDL for 7 days at which time the IMG was removed and the rats were ma intained for an additional 7 days (EDL+IMG). Epididymides were homogen ized and the number of spermatozoa in the caput and cauda epididymis w as counted. In EDL+7 rats, the caput epididymis was devoid of spermato zoa. The rate of transit of spermatozoa through the cauda epididymis o f EDL+7 rats was approximately 3.43 million/day. The total number of c auda epididymal spermatozoa in EDL+7 rats was reduced by 20% compared to sham-operated control rats. In EDL+14 rats, spermatozoa transited t he cauda epididymis at a rate of approximately 9.57 million/day, and t he total number of spermatozoa in the cauda epididymis was reduced by 73% compared to sham-operated controls. If the IMG was removed 7 days following EDL, spermatozoa transited the cauda epididymis at a rate co mparable to that observed in EDL+7 rats (3.39 million/day). Following IMG denervation of EDL+7 rats, cauda epididymal sperm numbers were mai ntained at levels observed in the EDL+7 rats. These data demonstrate t hat the transport of spermatozoa through the cauda epididymis is influ enced significantly by neuronal input from the IMG.