Ch. 9 Female Reproductive

Female reproductive organs

ovaries, uterus, fallopian tubes

ovaries

store and release the ovum

produce the 2 principal female sex hormones: estrogen and progesterone

consist of outer cortex layer (contains different-size follicles) and inner medulla (consist of vascular connective tissue)

uterus

composed of 3 layers: serous, muscular, and mucous

the muscular coat accounts for the bulk

the mucous membrane or endometrium

lined by columnar ciliated secretory epithelium

undergoes cycles of proliferation, differentiation to breakdown every 28 days in preparation for embryo implantation.

What is the effect of pulsatile GnRH release on gonadotropins?

Stimulates cyclic release of FSH and LH

Each cycle lasts 28 days and can be divided into 2 phases: Follicular and Luteal of approximately 14 days duration each.

Frequency determines relative secretion (fast pulses favor LH, slower favor FSH)

How does FSH promote follicular maturation at the cellular level?

Stimulates follicle growth and granuloma cells.

Increases estrogen production

Increases cAMP in granulosa cells, stimulates aromatase activity, and upregulates LH receptors.

What happens to follicles when FSH levels fall below a threshold?

Granulosa cell apoptosis → follicular atresia

Explain the estrogen feedback switch before ovulation.

• Low/moderate estrogen → negative feedback

• Sustained high estrogen → positive feedback → LH surge

Why does progesterone prevent a second LH surge?

Downregulates GnRH receptors and suppresses GnRH pulse frequency

What is the role of inhibin vs activin?

• Inhibin → ↓ FSH

• Activin → ↑ FSH

• Follistatin → inhibits activin