Cumulus oophorus in a secondary follicle.

In the antrum of this secondary follicle the follicular liquor formed a precipitate and stained eosinophilic. The oocyte has reached its maximum size. A large nucleolus can be seen with the nucleus. The zona pellucida separates it from the ring of granulosa cells surrounding it (corona radiata*). This in turn is attached to the cumulus oophorous which blends with the mural granulosa cells. The basal lamina of the granulosa cell is intact. Theca interna cells produce testosterone which is converted into estrogens by the granulosa cells. There is a high concentration of estrogens in the follicular liquor. (*Strictly speaking coronoa radiata refers to the rim of cells that surround the free floating oocyte that is released at ovulation. The term is used more liberally here.)PK1200. Original mag. 50x. H&E Secondary follicle. Cortex. Ovary. Female Reproductive System. Cat.