Effect of progesterone on human zona pellucida sperm binding and oocyte penetrating capacity

To determine if sperm exposure to P produces an enhancement in its fertilizing capacity. Sperm from fertile donors were exposed to P at 0.1 and 1.0μg/mL for 1 or 24hours. The effects on hyperactivated (HA) motility at 1 and 4hours, acrosome reaction (as determined by Pisum sativum agglutinin or T6/antibody techniques), on human zona pellucida binding (by using the hemizona assay), and on the penetrating ability (by using the zona-free hamster ova assay) were evaluated. Exposure to P at 1.0μg/mL enhanced HA motility after 1 and 4hours of P exposure, the acrosome reaction after 24hours’ incubation, the number of sperm bound/hemizona after 1-hour incubation, and the penetration rates in the hamster ova assay at both incubation intervals. Sperm exposure to P enhances its fertilizing capacity in fertile men, and further investigation is warranted as a possible treatment for male factor patients.