Structure and function of the mammalian egg zona pellucida

The zona pellucida is a thick extracellular coat that surrounds all mammali an eggs and preimplantation embryos. The zona pellucida supports communicat ion between oocytes and follicle cells during oogenesis; protects oocytes, eggs, and embryos during development, and regulates interactions between ov ulated eggs and free-swimming sperm during and following fertilization. Mut ant females that produce eggs that lack a zona pellucida are infertile. The functions of the zona pellucida during fertilization now can be ascribed t o certain of its glycoproteins. Here we describe some aspects of zona pellu cida structure and function as they relate to mammalian fertilization. (C) 1999 Wiley-Liss, Inc.