BIOL 001 Lecture Notes - Lecture 27: Oogenesis, Luteolysis, Zona Pellucida
6 Aug 2020
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Development of mature eggs (use fig 46. 11) Primordial germ cells (2n) ---->they undergo mitosis and generate cells called > Oogonia (2n), all form during embryonic development (no new oogonia after birth) Oogonia divide via mitosis > generate primary oocyte (2n) Stop at the middle of prophase i. At birth, individual has approx 1-2 million primary oocytes. By sexual maturity > approx 200,000 by sexual maturity. Dormant until puberty > acted on by hormones. Each primary oocyte kept within a follicle. Occurs in the follicle (structure within the ovaries) Follicle cells form a protective barrier around the primary oocyte. Zona pellucida: thick glycoprotein layer between follicle cells and oocyte. > primary oocyte grows, follicle cells proliferate (become larger) After approx 1 week the largest follicle continues, others stop (and are lost) It completes meiosis i 8-10 hours before release. As secondary oocyte matures > it moves to the surface of the ovary.
