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Physiology of theFemale ReproductiveSystem

Liu Wei

Department of Ob & GyRen Ji hospital

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Physiological Stages

• Neonatal period: birth---4 weeks

• Childhood: 4 weeks----12 years

• Puberty: 12 years---18 years

• Sexual maturation: 18 year---50 year

• Perimenopause: decline of ovarianfunction (40 years)----1 yearpostmenopause

• Postmenopause:

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Menstruation

• Menstruationcyclic endometrium sheds and bleeds due tocyclic ovulation

• Mense

1. Endometrium is sloughed (progesteronewithdrawal)

2. Nonclotting menstrual blood mainly comes

from artery (75%)3. Interval: 24-35 days (28 days). duration: 2-6

days. the first day of menstrual bleeding isconsideredy by day 1

4. Shedding: 30-50 ml

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Central reproductive hormones

• Hypothalamus-Pituitary-Ovary(H-P-O axis)

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Central reproductive hormones

• Neuroendocrine regulation

1. Gonadotropin-releasing hormone,GnRH

1) chemical structure

(pro)Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2

2) Synthesize and transport

nerve cells

hypothalamus

portal vein

pitutary

anterior lobe

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Central reproductive hormones

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Central reproductive hormones

3) Regulation of GnRH

Hypothalams

GnRH

Pituitary

FSH, LH

Ovary

E,P

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Central reproductive hormones

2. Gonadotropins

1) Composition (glycoprotein)

Follicle stimulating hormone,FSH

Luteinizing hormone,LH2) Synthesize and transport

Gonadotroph(pulse) 

Bloodcirculation

ovary

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Central reproductive hormones

3. Prolactin (PRL)

Regulated by the prolactin inhibiting factor (PIF)

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The Ovarian cycle

• Function of ovary

1. Reproduction

development and maturation of follicle;

ovulation2. Endocrine

estrogens, progesterone, testosterone

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The Ovarian cycle

• Cyclic changes of ovary1. The development and maturation of follicle

1) Primordial follicle: before meiosis

2) Preantral follicle: zona pellucida, granulosa cells(FSH receptor)

3) Antral follicle: granulosa cells (LH receptor), E↑ 

4) Mature follicle: E↑,P↑ 

Theca externa, theca interna, granulosa, follicularantrum, mound, radiate coronal

5) Follicular phase: day 1 to follicle mature (14days)

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The Ovarian cycle

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The Ovarian cycle

2. Ovulation1) First meiosis completed → collagen

decomposed → oocyte ovulated

2) Regulation

a) LH/FSH peak

E2↑(mature follicle) → GnRH ↑ (hypothalamus)→ LH/FSH peak (positive feedback)

b) P cooperationLH ↑ → P ↑(follicle luteinized before ovulation)

→positive feedback

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The Ovarian cycle

3. Corpus luteum

1) follicle luteinized after ovulation: luteal cells

2) LH → VEGF → corpus hemorrhagicum

3) Regressionnon fertilized → corpus albicans 

4) Luteal phase

Ovulation to day 1

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The Ovarian cycle

• sex hormones secreted by ovary1. Composition

Estrogen, progesterone, testosterone

2. Chemical structureSteroid hormone

3. Synthesis

Cholesterol→pregnenolone→androstenedione→ 

testosterone→estradiol

Δ5 or Δ4 pathway of estrogen production 

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The Ovarian cycle

4. Metabolism: liver

5. Cyclic change of E and P in ovary

1) Estrogen

a) E↑(day 7) → E peak (pre-ovulate) → E↓ → E↑ (1 day after ovulate) →E peak (day 7-8) → E↓ 

b) theca interna cells (LH receptor) → testosterone

c) Granulosa (FSH receptor) → estrogen

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The Ovarian cycle

2) Progesterone

P↑ (after ovulation) → P peak (day 7-8) → P↓ 

granulosa

progesterone

LH

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Ovarian responses

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The Ovarian cycle

• H-P-O axis1. Positive feedback

Sex hormones (E)↑ → GnRH or LH/FSH↑ 

E peak (≥200pg/ml) → LH/FSH peak → ovulation2. Negative feedback

Sex hormones (E)↑ → GnRH or LH/FSH↓ Follicular phase: E↑ → FSH↓ Luteal phase: E↑P↑ → LH/FSH↓(formation)

E↓P↓ → LH/FSH↑(regression) 

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The endometral cycle

• Proliferative phase

1. E↑(mitogen)→ stroma thickens and glandsbecome elongated → proliferative

endometrium2. Duration: 2 weeks

3. Thickness: 0.5mm → 5mm

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The endometral cycle

• Secretory phase1. P↑(differentiation) → secretory endometrium

2. Features

stroma becomes loose and edematousblood vessels entering the endometrium becomethickened and twisted

glands become tortuous and contain secretory

material within the lumina3. Duration: 2 weeks

4. Thickness: 5-6mm

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Change of Other genital organs

• Cervixendocervical glands (E↑)→ mucus(thin,clear,

watery) → maximal (ovulation)

endocervical glands (P↑)→ mucus(thick, opaque,tenacious)

• Vagina

Vaginal mucosa (E↑)→ thickening and secretorychanges

Vaginal mucosa (P↑) → secrete↓ 

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Physiological function of sex hormones

• Estrogen

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