Receptor activity of the hamster and mouse solubilized zona pellucida before and after the zona reaction

Capacitated golden hamster spermatozoa bound to the inner wall as to the outer surface of the zona pellucida, suggesting that the receptor-for-spermatozoa may occur throughout this egg envelope. When solutions of hamster zonae pellucidae were prepared by heating zonae in an aqueous buffer, receptor activity was retained and was stable to boiling. The addition of such solutions to capacitated spermatozoa (5 zonae/mul) prevented them from binding to eggs and fertilizing them. Solubilized mouse zonae were also partly effective, as would be predicted from the limited crossbinding between mouse and hamster gametes. Receptor activity was lost following the zona reaction.