PP2.H2.10 +D1 Atretic Follicles and Corpora Albicantes
Atretic Follicles and Corpora Albicantes:
- An atretic follicle is formed when an ovarian follicle breaks down
- This can occur at any stage of development prior to ovulation
- When primordial, primary or early secondary follicles become atretic follicles they quickly disappear without trace - the cells breakdown and cellular debris is removed by macrophages from the ovarian stroma
- When late secondary or Graafian follicles break down, there is a larger mass of cells, as well as the zona pellucida which surrounded the oocyte which must break down
- These atretic follicles may take a long time to be completely broken down, especially the zona pellucida
- Corpora albicantes are the "scars" of corpora lutea that have broken down
- They typically form an increasingly compacted mass of dense connective tissue
- These scars can be distinguished from atretic follicles because of:
- the lack of a zona pellucida (a corpus luteum only forms after the oocyte, surrounded by its zona pellucida, has been released from the ovary) and,
- the presence of some blood vessels within the scar (remnants of the rich vascular network of the endocrine gland of the corpus luteum)
Micrograph of Atretic Follicle:
- Note the general disorganisation of this (early) atretic follicle
- Remains of oocyte
- Zona pellucida
- Artefactual space
- Disorganised follicular cell layer
- Theca interna
NB The wavy band (stained red) between the follicular cell layer and the theca interna layer is the remains of the basement membrane onto which the stratified epithelium of the follicular cell layer was attached
