Capacitation of human spermatozoa by heparin.

Zona-free hamster oocytes were incubated in vitro with human spermatozoa treated with heparin for 5, 10, 20, and 30 min. Sperm penetration was observed 2, 4, and 8 h after insemination. Sperm penetration was successful in 40%, 60%, and 69% of the oocytes treated for 10 min with heparin. Feminine and masculine pronuclei were clearly identifiable. In these samples, 80% of the sperm was alive and there was approximately 68% progress motility. Live sperm were observed for up to 24 h. Since glycosamineglycan sulfates are normally present in the ooplasm, zona pellucida, follicular and uterine fluids, this might suggest a direct participation of heparin in human sperm capacitation.