The ovarian cycle + more

Roughly 28-day cycle with 2 processes
• Oogenesis- the production of oocytes (gametes)
• Folliculogenesis- growth and development of ovarian
follicles

Three phases
• Follicular phase
• Ovulation
• Luteal phase

Correlated with, but not the same as, the menstrual cycle

Oogenesis the process of egg formtion

  1. Diploid oogonia divide by mitosis to make primary oocytes.

  2. Primary oocytes start meiosis before birth but pause at prophase I until puberty.

  3. At puberty, one primary oocyte finishes meiosis I, making:

    • One secondary oocyte

    • One small polar body

  4. The secondary oocyte is released during ovulation.

  5. If fertilized by sperm, it completes meiosis II, forming:

    • One ovum (egg)

    • Another polar body

Folliculogenesis is the process by which ovarian follicles mature and get ready for ovulation

  1. An ovarian follicle is made up of an oocyte and its supporting cells.

  2. Theca cells and granulosa cells work together to make estrogen.

  3. The oocyte makes the zona pellucida (a protective layer), and fluid builds up around it.

  4. Out of all the follicles, one keeps growing and at ovulation, it releases the secondary oocyte along with surrounding granulosa cells from the ovary.