Female Reproductive Cycle [Menstrual Cycle]

FEMALE REPRODUCTIVE CYCLEA duration of 28 days is divided into 4 phases –
– Menstrual Phase
– Preovulatory Phase
– Ovulatory Phase
– Post Ovulatory Phase

(A) Menstrual Phase [ First 5 days of the cycle / mensus = month / Menstruation]

Influence of FSH (Follicle stimulating hormone)

Primordial follicles develops

Primary follicles & then change into secondary follicles.

A follicle that begins to develop in a particular cycle may ovulate after several cycle later.

Menstrual flow = 50-150 ml

Discharge occurs as decline in progesterone & estrogen

Cause release of prostaglandins

Arterioles become constrict, O2 deprived cells become die

Stratum functionalis sloughs off

(B) Preovulatory Phase – {Proliferative Phase}-

[ Time between the end of menstruation & ovulation / 6-13 days in 28 days cycle]

secondary follicles secrete estrogen (1 in both ovaries)

Become dominant follicle

Estrogen decreases secretion of FSH by dominant follicles

To stop the growth of other follicles

One mature dominant (graffian follicle) continue to enlarge (>20 mm in diameter)

With the help of estrogen by follicle stimulate and  repair of endometrium occurs

Mitosis in the cells of stratum basalis & produce a new stratum functionalis(4-10 mm diameter)

(C) Ovulation – [Rupture of graffian follicle & release of 2˚ oocyte, on 14th day of cycle]

 High level of estrogen in last part of pre-ovulatory phase

Exert positive feedback on cell that secrete LH & GnRH ( Gonadotropin releasing hormone )

GnRH promote release of FSH & LH additionally by anterior pituitary

LH causes rupture of graffian follicle

Note – Explusion of 2˚ oocyte about 9 hours after the peak of LH surge.

(D) Post Ovulatory Phase –

[ Secretory Phase / Luteal Phase / Time between the ovulation & onset of next mensus / from 15-28 day in 28 day cycle.]

 After ovulation mature follicle collapses

Basement membrane between granulosa cell & theca cell breaks down & mix to transformed into corpus luteum.

Corpus luteum secretes progesterone, estrogen, relaxin, inhibin [Luteal phase]

 If 2˚ oocyte not fertilized corpus luteum has lifespan of 2 weeks, becomes corpus albicans.

Progesterone, estrogen, inhibin decreases & GnRH, FSH & LH increases due to loss of negative feedback suppression by ovarian hormones.

  If 2˚ oocyte fertilized

Corpus luteum persist past its normal 2 week life span

Rescued from degeneration by hCG

hCG (Human chorionic gonadotropin) produced from chorion of embryo after 8th day fertilization

Progesterone, oestrogen produces by corpus luteum promote growth of endometrial gland.

Secretory activity of endometrial gland increases

Secretes glycogen [secretory phase]