Evidence supporting the existence of sperm maturation in the human epididymis

Zona-free hamster oocytes were used to evaluate the penetrating capacity of spermatozoa recovered from the caput, corpus and cauda segments of 5 human epididymides. The ability of spermatozoa to bind tightly to oocytes increased in spermatozoa from successive segments. However, only spermatozoa recovered from the cauda epididymidis were able to penetrate the oocytes (26%). These results suggest that, in man, a gradual process of sperm maturation occurs in the epididymis, as has been observed in numerous other species of mammals.