Is called zona pellucida (41 ZP; to the outer layer that surrounds the oocyte in mammals, separating him from the perivitelineo space. Is composed of several glycoproteins, grouped in three families: ZP1 ZP2 and ZP3, according to their functional and immunological properties, and has a total thickness of 0.015-0.020 mm.This area since the formation of the primary follicle, when epithelial cells turn cubic to cylindrical.
