LOSS OF CORTICAL GRANULES IN RABBIT EGGS EXPOSED TO SPERMATOZOA IN VITRO

Cortical granules are found in the unfertilized eggs of many invertebrates and vertebrates, including mammals, but are essentially absent in fertilized eggs (Austin, 1968). The extruded contents of the granules are thought to play a rôle in the prevention of polyspermy (Austin, 1961). In the sea urchin, the cortical granule breakdown occurs after sperm penetration has begun and appears to be a propagated reaction over the egg surface (Austin, 1961). Szollosi (1967), studying cortical granules in the hamster and rat, found that the granule breakdown in these species is generally activated by the attachment of a spermatozoon to an egg. Pikó (1969) reported that the reaction is triggered when membrane fusion and breakdown of the postnuclear cap region of the spermatozoon has begun. Thus, the presence