Tags: Anatomical Structure.
The zona pellucida (plural zonae pellucidae also egg coat or pellucid zone) is found in mammalian eggs. It is a glycoprotein membrane surrounding the plasma membrane of an oocyte. It is a vital constitutive part of the oocyte external but of essential importance to it. The zona pellucida first appears in unilaminar primary oocytes. It is secreted by both the oocyte and the follicular cells. The zona pellucida is surrounded by the cumulus oophorus.
