ABSTRACT
Zona pellucida glycoprotein 4 (ZP4) is a 540 amino acid glycoprotein located in the zona pellucida. It is synthesized by and surrounding the oocyte required for initial zona matrix formation and along with ZP3 during fertilization for inducing the acrosome reaction and inhibiting the binding of spermatozoa to zona pellucida in a time-and dose-dependent reaction.5
