Repropedia

A Reproductive Lexicon

NOTICE:

Ownership of this website has been transferred from Northwestern University to Michigan State University.
Please note that some site information may be inaccurate while adjustments to reflect this organizational change are made.

MOOC Advertisement

Learn More:
Get An Introduction to Reproduction

Learn more about the science of reproduction. Dr. Teresa Woodruff, creator of Repropedia, is offering a free online course exploring the world of reproduction.

Get Started!

zona pellucida

The zona pellucida is a membrane composed of four glycoproteins (ZP1-4) that surrounds the plasma membrane of the mammalian oocyte. It is important for inducing the acrosome reaction during fertilization and preventing polyspermy. The zona pellucida persists through pre-implantation embryo development, but the blastocyst must hatch out of the zona pellucida in order to undergo implantation in the uterus.