Physiology of Menstruation

Слайд 3

Слайд 4

Слайд 5

I- Onset of Puberty
Due to hypothalamic maturation with insensitivity of hypothalamus

to the inhibitory effect of estrogen. This leads to stimulation of pituitary gland with cyclic secretion of gonadotropins resulting in establishment of Ovarian Cycle.

Слайд 6

II- Ovarian Cycle
1- 1st half of the cycle (Follicular Phase):
Under effect

of FSH
It includes:
-Primordial follicle
-Pre-antral follicle
-Antral follicle
-Pre-ovulatory follicle (MGF)

Слайд 7

2- The middle of the cycle (Ovulation):
Def.: Rupture of MGF with

release of the oocyte
Timing: Middle of cycle (14th day)
Mech.:
- MGF→ estrogen →+ve feed back → LH surge → 1) reduction division of oocyte. 2)luteinization of granulosa (steroidogenesis) with synthesis of progesterone and PGs.
**PGF2α → 1) ++proteolytic enzymes (collagenase) & 2) intrafollicular tension

Слайд 8

3- 2nd half of the cycle (Luteal Phase)
Under effect of LH
It

includes:
1-Proliferation stage: Lutein & paralutein cells
2-Vascularization stage: Corpus hgicum
3-Maturity stage: max. E.& P. secretion
4-Degeneration stage: if no pregnancy occurs

Слайд 9

Fate of C.L.

Слайд 10

Слайд 11

Слайд 12

Слайд 13

Слайд 14

III- Changes in the endometrium

Слайд 15

3- Menstrual phase (Menstruation):
Def.: cyclic shedding of compact and spongy endometrium
Mech.:

When NO pregnancy occurs
P (from CL) → - LH → ↓ P&E (CL) → shrinkage of endometrium → tightening of spiral arterioles → ischemic necrosis of endomet. → destruction of lysosomes of endometrial cells → release of 1)phospholipase (formation of PGs: F2α>E2) & 2)plasminogen activator (formation of plasmin = fibrinolysin) → arrest of bleeding

Слайд 16