Ovarian cycle

Graphics in the diagram show the sequence of events, not movements. Photos show human ovaries. The mature follicle is about the size of a pea and projects from the ovary surface.

1. A follicle begins to mature;the primary oocyte enlarges and secretes proteins, and follicle cells around it divide.
2. Fluid-filled cavity begins to form in the follicle’s cell laye
3. Primary oocyte completes meiosis I and undergoes unequal cytoplasmic division to form a secondary oocyte and the first polar body.
4. Ovulation. Follicle wall ruptures, releasing the secondary oocyte and surrounding cells.
5. Follicle cells left behind after ovulation develop into a corpus  luteum that secretes hormones.
6. If pregnancy does not occur, the corpus luteum degenerates.