MORPHOLOGICAL CHANGES IN RABBIT SPERMATOZOA DURING PASSAGE THROUGH THE EPIDIDYMIS

Summary. The fertilizing ability of rabbit spermatozoa is acquired in passage through the epididymis, during which certain changes take place in the spermatozoon. It has been found here that a significant diminution (P<0·01) in acrosome width and length occurs during passage of spermatozoa from caput to cauda epididymis. Within-group analysis of the caput sperm group reveals a significant correlation (P<0·01) of acrosome width with the position of the cytoplasmic droplet on the midpiece. A large difference in the cytoplasmic droplet distribution is apparent between samples of spermatozoa from the cauda and caput epididymis, respectively. The occurrence and disposition of the droplet in either of these regions was not obviously altered following a series of successive ejaculations. The change in acrosome size during epididymal passage is discussed in relation to the development of fertilizing ability of rabbit spermatozoa.