The inner perivitelline layer (IPVL) contains the zona pellucida (ZP) proteins, in mammalian species one or more of the proteins acts as the sperm receptor. Sperm binding at the germinal disc (GD) to sperm receptors initiated the acrosome reaction to ultimately lead to fertilization, with the amount of sperm binding at the GD being a measure of female fertility. The goal of this research was to determine if differences in ZP protein level is static and if there are differences in relative abundance between locations in IPVL varies between genetic lines. There are no differences in ZPB1 or ZPB2 protein expression between the GD and NGD regions. The expression of ZPB2 is likely static, while the expression of ZPB1 is likely not static. Current results contradict previous studies that state ZPB2 may be the critical component of the sperm receptor and act ac a genetic selection marker for female fertility.
