Definition

Noun: A specialized, non-cellular layer that forms around an animal egg cell immediately following the entry of a sperm cell. Its primary function is to create a permanent barrier that prevents additional sperm from penetrating the egg, ensuring normal development with a single set of paternal chromosomes.

Usage

The term is used specifically in the fields of developmental biology, embryology, and zoology to describe a critical, rapid change in the egg's extracellular environment after fertilization.

Examples

• The swift formation of the fertilization membrane is a key event in blocking polyspermy.
• Under the microscope, researchers observed the elevation of the fertilization membrane within seconds of sperm entry.
• Experiments showed that without a proper fertilization membrane, the embryo often fails to develop correctly.

Advanced Usage

• "membrane elevation": This phrase is often used to describe the physical process of the fertilization membrane rising away from the egg's surface.
• The formation is sometimes called the "cortical reaction", referring to the underlying cellular process where cortical granules release their contents to form the membrane.

Variants and Related Words

• Vitelline membrane: The precursor layer surrounding the unfertilized egg, which is modified to become the fertilization membrane.
• Zona pellucida (in mammals): A glycoprotein layer around the mammalian egg that undergoes changes similar to the fertilization membrane's function, often termed the "zona reaction".

Synonyms

• Fertilization envelope (a less common but synonymous term).

Notes on Meaning

This term refers exclusively to a biological structure in animal reproduction. It is not used in a botanical context (plant fertilization) or in any metaphorical sense.

Noun

1. the membrane that forms around a fertilized ovum and prevents penetration by additional spermatozoon