Atretic Follicle - Med. Mag.
Follicles may undergo degeneration (atresia) at any time during their development. If a large follicle degenerates it collapses and granulosa cells will die sloughing into the antrum. The theca interna and externa layers also undergo changes. The basement membrane found between the granulosa and theca interna layers may hypertrophy and form a glassy membrane. The oocyte degenerates quickly yet the zona pellucida may persist for some time.