Oocytes and Oogenesis

reproduction and physiology

Oocyte anatomy

Oolemma, Zona Pellucida, Perivitelline Space (PVS), Polar bodies 1 & 2

Oolemma

Plasma membrane

Zona Pellucida

Protein coat surrounding the oocyte (thick wall to protect the egg)

PVS

The space between the oolemma and the zona pellucida (thick and thin layers)

Oocyte

Largest cell in the body

Female comparisons to males

Ovary - Testis

follicles

Granulosa cells - Leydig cells

Theca cells - Sertoli cells

Oogenesis

The formation, development and maturation of the female gamete

Ovary anatomy

Cortex (repro things)

• follicles

• oocytes

• corpus luteum

Medulla (non repro things)

• blood vessels

• lymphatics

• neurons

Tunica albuginea (protection)

Formation of Oogonia

PGCs start in yolk sac, travel to the gonadal ridge, mitosis begins

Gonadal ridge turns into the gonads

during mitosis the PGCs turn into primitive sex cords

XX chromosomes so no SRY protein meaning the sex cords regress

Prenatally

mitosis stops and the oogonia begin meiosis

What meiosis stage does meiosis become arrested?

Prophase I

what causes the oocyte to become arrested

the cAMP protein inactivates the maturation promoting factor, which leads to meiotic arrest.

What does LH do in oogenesis

Causes negative feedback to reduce the cAMP levels with activates the MPF and resumes meiosis.