A membrane surrounding an animal egg which becomes rapidly raised above the egg surface within seconds after fertilization, serving to prevent entry of a second sperm.
A membrane formed in some aquatic species from the vitelline membrane and cortical granules immediately after sperm penetration into the ovum. It is thought to prevent polyspermy by making the egg impenetrable to other sperm.
membrana de fertilizacion (o fecundacion)] a membrane formed by an egg in response to its union with a sperm, which grows rapidly from the point of union and covers the egg, excluding other sperm.