Anatomic.us > Reproductive System > Ovum

Zona Pellucida

Zona pellucida is basically a layer of glycoproteins around the plasma membrane of egg (ovum). It is located within the follicles residing in the ovary of a female. This layer is secreted by the egg itself and also by the granulosa cells of the follicles.

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Zona Pellucida


STRUCTURE

Zona pellucida is a thick extracellular matrix. It is of three different types ZP1, ZP2 and ZP3. ZP3 glycoprotein is the most important one in the humans. Its main function is to facilitate the fertilization. After binding to a single sperm, it ruptures and is degenerated and gets replaced by the trophoblastic layer.

FUNCTION

It facilitates the fertilization in following way.

  • It binds spermatozoa with the egg and inhibits other sperms from binding, hence prevents polyspermy (fusion of more than one sperms with the egg).
  • It induces acrosome reaction which is characterized by the release of acrosomal proteins from the vesicle and allows only one sperm to reach the egg.
  • ZP1 causes the crosslinking of ZP2 and ZP3.
  • ZP2 facilitates the binding phenomenon
  • ZP3 causes species-specific sperm binding

 



STRUCTURE

Zona pellucida is a thick extracellular matrix. It is of three different types ZP1, ZP2 and ZP3. ZP3 glycoprotein is the most important one in the humans. Its main function is to facilitate the fertilization. After binding to a single sperm, it ruptures and is degenerated and gets replaced by the trophoblastic layer.

FUNCTION

It facilitates the fertilization in following way.

  • It binds spermatozoa with the egg and inhibits other sperms from binding, hence prevents polyspermy (fusion of more than one sperms with the egg).
  • It induces acrosome reaction which is characterized by the release of acrosomal proteins from the vesicle and allows only one sperm to reach the egg.
  • ZP1 causes the crosslinking of ZP2 and ZP3.
  • ZP2 facilitates the binding phenomenon
  • ZP3 causes species-specific sperm binding

 

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