Question

A clear non-cellular membrane present in a growing follicle is _ _ _ _ _ _ _ _.
A. Corona Radiata
B. Corpus Albicans
C. Corpus luteum
D. Zona pellucida

Answer 1

Hint:Follicle is simply a fluid-filled sac that comprises an immature egg or oocyte. On the basis of the number of layers of granulosa cells, the development of theca tissue, and the expression of a small cavity or antrum the early stages of follicle development can be categorized into 3 classes which are primary, secondary, and early tertiary follicles.

Complete answer:
● Corona Radiata is defined as a cellular layer almost bordering to the zona pellucida layer inside the ovum and derived from the cumulus oophorus.
● Corpus Albicans is a Latin word non-cellular. It is an ovarian defect composed of connective tissue that forms after the degeneration of the corpus luteum and a process is known as luteolysis.
● Corpus Albicans is mainly made of collagen and remains on the ovary for a few months. It secretes:
1. Theca Interna, which is an inner layer of the cells enveloping the primary oocyte in the tertiary follicle existing inside the ovary.
2. Membrane granulosa, which is made up of the granulosa cells existing in the internal coating of the vast ovarian follicles.
● Zona pellucida is a Latin word which means a transparent zone.
● Zona Pellucida is a specialized extracellular matrix enclosing the evolving oocyte ( i.e. egg or ovum) inside each follicle within the ovary. It is a non-cellular glycoprotein membrane around the ovum.
So, the correct answer is D i.e. Zona pellucida.

Note: The main variation among zona pellucida and corona radiata i.e. zona pellucida is a secretary glycoprotein layer that encloses the plasma membrane of mammalian ovum while corona radiata is a follicle cell layer that surrounds zona pellucida. Corona radiata causes a stroke known as lacunar stroke or small vessel stroke.