SPERM OOCYTE INTERACTION - STUDIES ON THE KINETICS OF ZONA-PELLUCIDA BINDING AND ACROSOME REACTION OF HUMAN SPERMATOZOA

Successful sperm-oocyte interaction depends, among other things, on sp erm capacitation, which is defined by acrosomal and motility alteratio ns. In the study described here the authors evaluated different aspect s of this gamete interaction in humans. Specifically, the authors stud ied (1) the relationship between the number of spermatozoa bound to th e zona pellucida and sperm concentration and incubation period, (2) th e capacitation status and kinetics of acrosome reaction among the zona -bound spermatozoa, and (3) the effect of human follicular fluid on th e zona-binding potential and acrosome status of spermatozoa from diffe rent men. The results indicated a concentration of 10(7) cells ml-1 af ter 15 min of coincubation to be the optimum for zona binding. The num ber of sperm bound after 0, 3 and 5 h of incubation was the same. In a ddition, spermatozoa incubated for 3 or 5 h under-went the acrosome re action (range 9-43%) on the zona surface within 15 min of binding. The maximum percentage of acrosome-reacted spermatozoa was reached after 60 min of binding. Follicular fluid affected the sperm populations sel ectively, since it did not influence zona binding capacity in all case s. The data enhances the authors' understanding of critical events occ urring before fertilization.