Graafian Follicle
Definition
Synonym : ovarian follicle
Fluid-filled capsule that surrounds and protects the developing egg cell inside the ovary during the menstrual cycle.
After the egg cell has been released, the follicle remains and is known as a corpus luteum.
Features
The graafian follicle is contained in the germinal epithelium of the cortex of the ovary
Ovarian follicles are in various stages of maturity
The ovarian follicle is a large, fluid-filled antrum
With an eccentric oocyte.
Before puberty the ovaries are inactive
But the stroma already contains immature (primordial) follicles
During the child bearing years one ovarian follicle (Graafian follicle) matures, ruptures and releases its ovum into the peritoneal cavity - ovulation
The Graafian follicle contains cells called granulosa - the granulosa is divided into two groups : -
1. the zona granulosa a thin layer along the periphery of the follicle
2. the corona radiata which surrounds the oocyte.
The oocyte has undergone the first meiotic division, giving rise to a secondary oocyte and the first polar body.
The secondary oocyte is now arrested in metaphase of the second meiotic division
It will remain so until fertilization.
The Graafian follicle represents the final stage of follicular development before ovulation.
After ovulation
The follicle lining cells develop into the corpus luteum (yellow body)
Corpus luteum degenerates into an inactive mass of fibrous tissue called corpus albicans if fertilization does not occur.
