Dissolution of rabbit zona by sperm acrosomal extract: effect of calcium (1).

The acrosomal extracts from rabbit spermatozoa were more effective in dissolving the zona pellucida of the rabbit ova in the absence than in the presence of Ca2+. The extracts had high proteolytic activity but low esterolytic activity at alkaline pH in which pH effective zona hydrolysis occurred. The results suggest that acrosomal proteinases in addition to acrosin may be involved in the zona penetration.