Influence of abdominal temperature on epididymal function in the rat and rabbit.

Abstract

AbstractThe effects of body temperature on sperm maturation and sperm storage in the epididymis have been studied in rats and rabbits by surgical reflection of the epididymis into the abdomen without disturbing its continuity with a functional scrotal testis. Rats so treated remained fertile during a period of 13 months, as judged by a sequence of normal litters born to their female cage mates, and cryptepididymal rabbits remained fertile for four months or more according to the individual, as evidenced by eggs fertilized and litters born after artificial insemination or natural mating. By contrast, spermatozoa confined by ligatures within an abdominal cauda epididymidis never retain their potential for motility for more than a brief period (5 days in rat; 8–10 days in rabbit), as compared with several weeks in contra‐lateral scrotal controls. It is uncertain whether their early death at abdominal temperatures resulted primarily from a suppressive effect of the temperature on the spermatozoa themselves, or on the caudal epithelium.Because of an increasing presence of apparently immature spermatozoa in the ejaculate of the first cryptepididymal rabbit between 7 and 11 months postoperatively, the rate of sperm transport through the epididymis of seven cryptepididymal rabbits was estimated by labelling with tritiated thymidine. As judged by the time of appearance of labelled spermatozoa in the ejaculate, transposition of the rabbit epididymis to the abdomen ultimately causes a progressive increase in the rate of sperm transport through it from a normal of nine days to two to five days in the cryptepididymal state.Thus, although maturation may eventually be compromised to some degree because of an increased rate of sperm passage, and sperm storage is inhibited, abdominal temperature apparently does not alter the essential biochemical nature of the epididymal milieu required for maturation. These results are reviewed in light of the suggestion (Bedford, '78) that the cauda epididymidis has been the prime mover in scrotal evolution.