Oocyte and corona together are called the cumulus oophorous. Oocyte is approaching maturity as many internal changes have occurred. Oocyte is full sized by antral formation. Thecal cells have great capacity to produce testosterone but limited ability to convert it to estrogens. Granulosa have significant capacity to convert testosterone to estrogen but can not synthesize test.
Follicle bulges from surface of ovary into abdominal cavity.
Primary oocyte to secondary oocyte. Follicle wall thins out at point where it joins the surface of the ovary. Digestive enzymes secreted by the granulosa cells remove the intercellular material that holds cells together. This process continues until wall is too weak to resist breaking under declining pressure of the follicular fluid. See Bloom and Fawcett-page 821 for more details.