IVY CHEN, MPH
Lecturer, ivychen@berkeley.edu

IB 140: Human Sexuality & Reproduction

Diagrams from Lecture:

Follicle Development, Oogenesis & Estrogenesis

Ovary with follicles in varying stages and corpus luteum

Graaffian Follicle

Another slide of a graafian follicle:

Close-up of oocyte and surrounding GCs: this is what gets ovulated

Follicle Development

Oogenesis

Before Birth

•1. Oogonium (2N) undergo many mitotic divisions

•2. After last mitotic divison, result is primary oocyte (2N)

•3. Primary oocyte begin 1^st meiotic divison, but is stopped at Prophase

Special notes:

•** A female baby is born with only 1º oocytes in primordial follicles.

•** All stages of follicular development happens around a 1º oocyte (except for very late Graffian just before OV)

Beginning at puberty:

•4. The selected primary oocyte completes 1^st meiotic division around time of ovulation

•5. Products = 2º oocyte & 1^st polar body

•6. 2º oocyte will begin 2^nd meiotic divison, arrested at Prophase

•7. If fertilized, 2º oocyte complete 2^nd meiotic divison.

•8. Products = 1 ovum (now fertilized) & 2^nd polar body

•** you get 1 final ovum form 1 primary oocyte

2-cell Mechanism of Estrogenesis