Localization of Acrosomal Proteinase after Vesculation of the Acrosome

The freshly ovulated egg is covered by the zona pellucida and follicular-cell layer. The former is reported to dissolved by acrosomal proteinase and the latter may be dispersed by hyaluronidase. If these two enzymes have different targets, two possibilities can be taken into consideration concerning the timing of release of the two enzymes from the acrosome. Since hyaluronidase is considered to be released immediately after the acrosomal reaction at the follicular-cell layer, this work was undertaken to examine the timing of release of acrosomal proteinase after vesiculation of the acrosome, by demonstrating the site of the proteinase histochemically. The results indicated that the acrosomal proteinase disappeared immediately after vesiculation of the acrosome. This result suggests that spermatozoa that show vesiculation of the acrosome in the follicular-cell layer probably lose acrosomal proteinase in this layer. Thus the spermatozoon probably does not attack the follicular-cell layer and zona pellucida, one by one by release sequential of hyaluronidase and acrosomal proteinase.