33. FIBROUS GRAFFIAN FOLLICLE

A Graafian follicle is the final, mature stage of an ovarian follicle (

in humans) before ovulation, containing a fluid-filled cavity (antrum) and a secondary oocyte. It features an inner layer of granulosa cells and outer connective tissue layers (theca interna/externa) that produce high levels of estrogen before rupturing to release the egg. 

ScienceDirect.com +5

Key Characteristics and Structure

• Structure: Composed of a large central antrum, a peripheral layer of granulosa cells, and theca layers.
• Oocyte Position: The oocyte is located eccentrically, surrounded by the cumulus oophorus.
• Theca Layers: The connective tissue surrounding the follicle differentiates into a vascularized theca interna (hormone production) and a fibrous theca externa.
• Maturation: It develops from a secondary follicle under FSH and LH influence, often termed the preovulatory follicle.

• Fate: During ovulation, the follicle ruptures, releasing the oocyte, and the remaining structure transforms into the corpus luteum. 

  University of Leeds +5

Clinical Significance

• Ovulation: The Graafian follicle is essential for the release of a mature egg.
• Hormone Production: It produces high levels of estrogen, which triggers the LH surge for ovulation.
• Follicular Cysts: If a Graafian follicle fails to rupture and continues growing, it may form a functional ovarian cyst.