MATURATION OF MONKEY SPERMATOZOA IN THE EPIDIDYMIS WITH RESPECT TO THEIR ABILITY TO UNDERGO THE ACROSOME REACTION

Spermatozoa obtained along the length of the epididymides from five ma caque monkeys (Macaca fascicularis) were examined for their ability to undergo the acrosome reaction under basal conditions and when stimula ted with the calcium ionophore A23187. Under basal conditions (2.5 hou rs incubation in potentially capacitating medium) few epididymal sperm cells displayed the loss of acrosome as judged by staining with peanu t agglutinin lectin that binds to the outer acrosomal membrane, regard less of the epididymal region from which they were retrieved. By contr ast, there was a marked difference in response to short (0.5 hour) inc ubation with the calcium ionophore A23187, which induced acrosome reac tions in the majority of caudal sperm: caput sperm failed to respond a t all and corpus sperm were about 50% as responsive as caudal spermato zoa. There is thus a development of the ability to respond to the iono phore upon maturation. Ejaculated spermatozoa from the same monkeys di splayed a higher rate of basal acrosomal loss but a slightly lower sti mulated response than mature epididymal spermatozoa. With these matura tional aspects, monkey epididymal sperm can serve as a model for the s tudy of human sperm maturation.