Question

Innermost layer of Graffian follicle is
A. Membrana granulosa
B. Corona radiata
C. Discus proligerus
D. None of the above

Answer 1

A mature ovarian follicle is called Graffian follicle.It is the follicular stage comes after the first meiotic division but before the ovulation. It consists of a large central follicular cavity or antrum and is surrounded by two layers called theca externa and theca interna. The ovum into the oviduct contains three layers- oocyte, zona pellucida and corona radiata.

Complete answer:
Ovaries are the essential or primary reproductive organs of females. Each ovary is surrounded by mesovarium and internally differentiates into- outer germinal epithelium, a delicate sheath of tunica albuginea, a cortex and medulla. The process of formation of mature female gametes is called oogenesis.
-Certain cells of germinal epithelium are called oogonia. The ovarian follicles are a group of actively dividing cells.
-A growing or primary follicle contains a large central cell or oocyte surrounded by a single layer of small cubical follicle cells.
-A secondary follicle develops a transparent non-cellular area called zona pellucida around the oocyte.
-Covering is called theca divided into outer theca externa and inner theca interna.

Finally a fully mature stage is termed Graafian follicle. It consist –
-Large central follicular cavity or antrum with a fluid called liquor folliculi.
-The follicular cells lining the cavity are termed membrana granulosa.
-The mass of cells which surrounds and attaches the primary oocyte of the follicle wall is called discus proligerus or cumulus.
-Next to the zona pellucida, cells of inner margin of cumulus present a characteristic radial arrangement and termed corona radiata.Cell of corona radiata are held together by hyaluronic acid and disperse before implantation.
-When Graafian follicle releases into the oviduct, the ovum will contain three layers:- oocyte, zona pellucida and corona radiata. The innermost layer is called corona radiata.

Hence, the correct answer is option (B).

Note: Graafian follicular cells form a cellular sheath called membrana granulosa and cellular mass called cumulus ovaricus covering the oocyte. Cumulus oophorus or cumulus ovaricos differentiates into outer discus proligerus and inner corona radiata.