Induction of zona reaction in golden hamster eggs by cortical granule material.

BRADEN et al.1 have shown that the zona pellucida of mammalian eggs changes after fertilization so that penetration of further spermatozoa is greatly reduced. Austin and Braden2 inferred that this zona reaction was due to the action of the cortical granule material which is released from the egg into the perivitelline space shortly after sperm entry into the egg cytoplasm. We wish to present experimental evidence to support this inference.