Phorbol myristate acetate induces ruffling of the acrosome of human sperm.

Objective: To determine the effect of phorbol myristate acetate (PMA) on human acrosome morphology and the acrosome reaction.

Design: Controlled experiments on sperm and unfertilized oocytes from volunteers.

Setting: Academic research and teaching tertiary hospital.

Patient(s): Sperm samples were from normospermic men and unfertilized oocytes from IVF patients.

Main Outcome Measure(s): Acrosome morphology was assessed by using transmission and scanning electron microscopy. The acrosome reaction was assessed by using fluorescein-labeled Pisum sativum agglutinin.

Result(s): PMA induced acrosome ruffling, indicated by a marked wavy appearance. A significant correlation was found between PMA-induced ruffling and PMA enhancement of the zona pellucida-induced acrosome reaction. Protein kinase C inhibitors bisindolylmalemide I and sangivamycin had no effect on PMA-induced acrosomal ruffling, but actin polymerization inhibitors cytochalasin B and cytochalasin D significantly decreased PMA-induced acrosomal ruffling. In contrast, bisindolylmalemide I, sangivamycin, cytochalasin B, and cytochalasin D significantly decreased both the zona pellucida-induced acrosome reaction and the PMA enhancement of the zona pellucida-induced acrosome reaction.

Conclusion(s): PMA-induced acrosomal ruffling involves actin polymerization, possibly independent of conventional protein kinase C. Acrosomal ruffling is involved in the PMA augmentation of the zona pellucida-induced acrosome reaction.