Avian sperm-egg interaction: perivitelline layer possesses receptor activity for spermatozoa

Sperm-egg interaction in mammals is initiated by the binding of spermatozoa to the zona pellucida (ZP), an acellular coat completely surrounding the vitelline membrane of unfertilized eggs. The perivitelline layer (PL) of the ovum of the hen is analogous to the mammalian ZP. In vitro incubation of the PL with spermatozoa results in fragmentation of the PL. The PL promotes the acrosome reaction whereby sperm acrosomal enzymes are released; the enzymes in turn dissolve the PL. The present study was conducted to determine if the PL removed from chicken ova, recovered immediately after ovulation, possess sperm-receptor activity. The results suggest that the solubilized PL does contain one or more components which behave in a manner analogous to sperm-receptors. Pretreatment of spermatozoa with solubilized PL prevented their subsequent attachment to and fragmentation of the intact PL which was observed with untreated spermatozoa.