Ovary: secondary follicle

The primary oocyte, arrested in prophase of the first meiotic division, is surrounded by the zona pellucida. Stratum granulosal cells form a hillock surrounding the oocyte, termed the cumulus oophorus; the first row of cumulus cells outside the zona pellucida is the corona radiata. The cumulus oophorus, including the corona, accompanies the oocyte during ovulation.

The primary oocyte, arrested in prophase of the first meiotic division, is surrounded by the zona pellucida. Stratum granulosal cells form a hillock surrounding the oocyte, termed the cumulus oophorus; the first row of cumulus cells outside the zona pellucida is the corona radiata. The cumulus oophorus, including the corona, accompanies the oocyte during ovulation.

The primary oocyte, arrested in prophase of the first meiotic division, is surrounded by the zona pellucida. Stratum granulosal cells form a hillock surrounding the oocyte, termed the cumulus oophorus; the first row of cumulus cells outside the zona pellucida is the corona radiata. The cumulus oophorus, including the corona, accompanies the oocyte during ovulation.

The primary oocyte, arrested in prophase of the first meiotic division, is surrounded by the zona pellucida. Stratum granulosal cells form a hillock surrounding the oocyte, termed the cumulus oophorus; the first row of cumulus cells outside the zona pellucida is the corona radiata. The cumulus oophorus, including the corona, accompanies the oocyte during ovulation.

The stratum (or membrana) granulosum surrounds the antrum. Under the influence of LH from the pituitary, the theca interna produces testosterone, which is transported to granulosa cells for chemical modification (aromatization) to form estrogen. Granulosa cells are stimulated by the action of FSH from the adenohypophysis.

The stratum (or membrana) granulosum surrounds the antrum. Under the influence of LH from the pituitary, the theca interna produces testosterone, which is transported to granulosa cells for chemical modification (aromatization) to form estrogen. Granulosa cells are stimulated by the action of FSH from the adenohypophysis.

The theca externa surrounds the theca interna and serves as a reserve-cell source for the interna.

A single, large, fluid-filled antral space is indicative for a secondary follicle.

During the follicular phase of the ovarian cycle (Days 1-14), follicles housing oocytes are growing and secreting estrogen.

On Day 14 a surge of LH stimulates a secondary follicle to greatly enlarge and form a mature or Graafian follicle. Simultaneously, the primary oocyte completes the first meiotic division to form a secondary oocyte and the first polar body. At ovulation, the ovarian-follicular wall ruptures, releasing the secondary oocyte and its polar body, enclosed in the cumulus oophorus.