The mouse zona pellucida: folliculogenesis, fertility and pre-implantation development.

Perinatally, oocytes within the mouse ovary become surrounded by a layer of flattened granulosa cells and form primordial follicles. The subsequent accretion of the zona pellucida between the oocytes and granulosa cells provides a biochemical marker of folliculogenesis. In mice, the zona matrix is composed of three proteins (ZP1, ZP2, ZP3).

Incorporation of mouse zona pellucida proteins into the envelope of Xenopus laevis oocytes.

All vertebrate eggs have extracellular matrices, referred to as the zona pellucida in Mus musculus and the vitelline envelope in Xenopus laevis. The mouse zona, composed of three sulfated glycoproteins (ZP1, ZP2, ZP3), is critical for fertilization and early development, and mice lacking a zona pellucida produce no live offspring. The primary structures of mouse ZP1 (623 amino acids), ZP2 (713 amino acids) and ZP3 (424 amino acids) have been deduced from full-length cDNAs, but posttranslational modifications result in mature zona proteins with molecular masses of 200-180 kDa, 140-120 kDa, and 83 kDa, respectively.