Proteolytic activity of guinea pig spermatozoa after induction of the acrosomal reaction in vitro.

After inducing the acrosomal reaction in guinea pig spermatozoa in vitro, the sperm were tested for proteolytic activity by applying them to membranes of fixed gelatin. One to 5% of them showed slight evidence of proteolytic activity, while the rest were completely negative. Sperm that had retained their acrosomes throughout the incubation period displayed intense proteolytic activity. These results suggest that proteinases may be lost from spermatozoa as a result of the acrosomal reaction.