Zona pellucida
Zona Pellucida
Zona Pellucida (pronunciation: /ˈzoʊnə pɛˈluːsɪdə/) is a glycoprotein layer surrounding the plasma membrane of mammalian oocytes. It plays a crucial role in oogenesis, fertilization, and preimplantation embryonic development.
Etymology
The term "Zona Pellucida" is derived from Latin, where "zona" means "zone" and "pellucida" means "transparent". This refers to the transparent, gel-like layer that surrounds the egg cell in mammals.
Function
The Zona Pellucida has several important functions in reproduction. It binds sperm, initiates the acrosome reaction, blocks polyspermy, and provides a substrate for sperm-oocyte binding. After fertilization, the Zona Pellucida helps to prevent the blastocyst from implanting in the wrong place, such as in the fallopian tube, which could lead to an ectopic pregnancy.
Composition
The Zona Pellucida is composed of three main glycoproteins, ZP1, ZP2, and ZP3. These proteins are synthesized and secreted by the oocyte during oogenesis. The exact composition and structure of the Zona Pellucida can vary between species.
Related Terms
- Oocyte: The female germ cell involved in reproduction.
- Oogenesis: The process of female gamete formation in animals.
- Fertilization: The union of a male and a female gamete to form a zygote.
- Preimplantation embryonic development: The stages of embryonic development before the embryo implants into the uterus.
- Acrosome reaction: A process in the fertilization of mammalian eggs where the cap-like structure on the head of the sperm, the acrosome, releases its contents.
- Polyspermy: The fertilization of an egg by more than one sperm.
- Sperm-oocyte binding: The binding of a sperm to an oocyte, which is a crucial step in fertilization.
- Ectopic pregnancy: A complication of pregnancy in which the embryo attaches outside the uterus.
External links
- Medical encyclopedia article on Zona pellucida
- Wikipedia's article - Zona pellucida
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