Question

The primary egg membrane of mammalian egg is termed as
(a)Chorion
(b)Corona radiata
(c)Zona pellucida
(d)Vitelline membrane

Answer 1

Hint: The primary egg membrane is a jelly-like coat secreted by the granulosa cells. It is a non- cellular covering to the mammalian egg. This membrane is essential for an acrosome reaction.

Complete answer:
Zona pellucida protects the egg when it releases from the ovary. It is a translucent covering of glycoproteins that is surrounded by the mammalian egg. This membrane is required for the binding of spermatozoa which allows species-specific fertilization to prevent polyspermy. Therefore the primary egg membrane is zona pellucida.

Additional Information: -The mature egg is covered by a cell membrane or plasmalemma.
-The mammalian egg is produced in the ovary and eventually released into the fallopian tube during ovulation.
-Zona pellucida has a sperm binding protein or sperm receptor. There are four types of sperm receptors: ZP1, ZP2, ZP3, and ZP4.
-When the sperm able to penetrate from the extracellular matrix of the zona pellucida that is present around the egg is referred to as successful fertilization.
-In a non-mammalian egg, the zona pellucida is known as a vitelline envelope.

So, the correct answer is, ’ Zona pellucida’.

Note: -By birth, the mammalian egg is covered by a layer of cells or germinal epithelium surrounding an immature egg.
-The FSH or follicle-stimulating hormone secreted by the pituitary into the bloodstream promotes the growth of the egg.
-After the maturation of the egg, the pituitary releases LH or luteinizing hormone which causes the egg’s release called ovulation.