ASSESSMENT OF HUMAN SPERM FUNCTIONAL-CHANGES AFTER IN-VITRO COINCUBATION WITH CELLS RETRIEVED FROM THE HUMAN FEMALE REPRODUCTIVE-TRACT

Human spermatozoa must undergo functional changes prior to fertilizati on; however, the site of this physiological event is still unclear. To evaluate the influence of the female reproductive tract on sperm fert ilizing capacity, fertile sperm samples were coincubated with endometr ial, oviductal, granulosa and cumulus cells, follicular fluid and mate rnal serum. Sperm penetration into the zona-free hamster ova and motio n parameters were measured daily for 72 h. Compared to control samples , endometrial and oviductal cell cultures did not alter sperm fertiliz ing capacity or their movement characteristics. Sperm coincubated with follicular fluid, granulosa or cumulus cells exhibited a significantl y higher ability to penetrate zona-free hamster ova for up to 48 h. Sp erm motility increased at 4 h in the presence of follicular fluid and serum. At 24 h sperm velocity and amplitude of lateral head displaceme nt significantly declined in sperm samples exposed to serum, and veloc ity also declined in follicular fluid and with coincubation using ovar ian follicle cells. Sperm motility and velocity decreased at 48 h in t he presence of serum, follicular fluid, cumulus or granulosa cells. Ou r findings may suggest that specific secretory factors produced in the human pre-ovulatory ovarian follicle enhance human sperm fertilizing capacity.