Morphological changes of cauda epididymis, sperm infiltration into cauda epididymis, sperm storage and sperm disappearance of cauda epididymis in Rhinolophus ferrumequinum korai (Chiroptera: Rhinolophidae)

Abstract

In this study to investigate the male reproductive cycle of Rhinolophus ferrumequinum korai, we focused on monthly morphological changes of cauda epididymis, sperm infiltration into cauda epididymis, sperm storage and sperm destruction. The caudal epididymal reproductive cycle consisted of two successive purge stages. The first stage of sperm disappearance occurred from April to June. This was a preparation phase for accepting new sperm produced by spermatogenesis, and entailed removing long-stored spermatozoa from the cauda epididymis during the long hibernation period. The second stage of sperm disappearance occurred from July to August, to remove malformed spermatozoa and other residues that were formed during the spermatogenesis process. Therefore, cauda epididymis cleansing lasts about 5 months, from April to August. This period is called the cleansing period. Sperm destruction was achieved by regulating leukocyte phagocytosis and the secretion and uptake by epithelial cells of cauda epididymis. Compared to the author’s previous studies, morphological traits of the cauda epididymis changed 1 month earlier. This suggests that temperature increase can impact reproductive development of the epididymis. Caudal epididymal sperm did not show any sudden morphological change during the long hibernation period after mating. This might be related to a low metabolic rate during hibernation.