Interaction With Cumulus Cells And The Zona Pellucida

A typical mammalian egg is surrounded by an outer layer of about 3,000 cumulus cells embedded in an extracellular matrix rich in hyaluronic acid. It is suggested that the fertilizing sperm with it's acrosome intact, passes through the cumulus cell layer. The zona pellucida (ZP), a glycoproteinaceous matrix surrounding the mammalian oocyte plays an important role in species specific sperm-egg binding, induction of acrosome reaction in the ZP bound spermatozoa, avoidance of polyspermy and protection of the embryo prior to implantation. The human ZP matrix is composed of 4 glycoproteins designated as ZP1, ZP2, ZP3 and ZP4.

Summary from Reactome (R-HSA-2534343), read 2026-09-23.