Menstruation Cycle (M.C)
Menstruation cycle is a cycle of events occurs in a rhythmic pattern in the internal reproductive organ of a female. M.C occurs during the reproductive life of a woman from puberty till menopause. Ideally the duration of menstruation cycle is 20-40 days under normal condition, but commonly it is of 28 days. Because 28 days are roughly one month so it is also known as monthly cycle.
During the M.C several events are taking place so this cycle is divided into following four phases which are as follows
(A). Menstrual Phase 1-5 days
(B). Proliferation Phase 6-13 days
(C). Ovulation 14th day
(D). Secretary Phase 15-28 days
(A). Menstruation Phase
This is the primary phase of menstruation cycle which occurs from 1-5 days of M.C. During menstrual phase blood stained vaginal discharge occurs in the woman.
The total amount of discharge is 70-80 ml.
This menstrual discharge contains
• 30-40 ml of blood
• 35-40 mk of endometrial cells, glands, mucus membrane etc.
The menstrual phase occurs because of decreased level of estrogen & progesterone hormone in the blood of woman. Actually on 28th day of last menstruation cycle the endometrium is 8 cm in thickness (highest) but blood level of estrogen & progesterone is lowest.
In the absence of estrogen and progesterone hormone the endometrial tissue starts to die and hence endometrial shedding off starts. Now this shedded off endometrial tissue and blood comes out from the vagina as menstrual discharge. On the fifth day thickness of endometrium is left 2 mm.
(B). Proliferation Phase
It is the secondary phase of menstruation cycle, which takes place from the 6-13th day. During this phase of M.C proliferation occurs in the ovary as well as in the uterus.
Actually for first 5 days secretion of estrogen and progesterone is stopped at 20. This message is reached to the hypothalamus. Now as a response the hypothalamus secretes GnRH (Gonadotropin Releasing Hormone). Now this GnRH does stimulates pituitary gland & as a response the pituitary gland secretes FSH & LH hormone.
Now FSH & LH hormone does stimulates ovarian follicle. This ovarian follicle is present in primordial stage. Now the ovary starts secretion of estrogen & progesterone hormone once again from 6th day of M.C.
Because of effect of estrogen & progesterone hormone new cells, gland starts to develop at the endometrium of uterus. So the thickness of endometrium becomes 4 mm at the end of 13th day of M.C.
On the other hand inside the ovary thr primordial follicle is developed into primary follicle, then into secondary follicle & eventually into graffian follicle. So from several hundred of primordial follicles only one graffian follicle is developed on 13th day of M.C. This mature graffian follicle does have a mature ovum inside it.
(C). Ovulation Phase
Ovulation is a phase of release of ovum from thr ovary during menstruation cycle. The ovulation takes place on 14th day of a menstruation cycle of 28th day.
Actually on the 13th day of M.C the graffian follicle is completely mature & the endometrium is also prepare for conception. This message is reach to the pituitary gland & in response the pituitary gland secretes high amount of FSH & LH hormone, which is known as FSH surge, LH surge. This LH surge is actually responsible for ovulation. Now the graffian follicle moves to the periphery of ovary and then kn ovum is released from graffian follicle into the pelvic cavity.
Now this ovum is caught by ovarian fimbraie of fallopian tube & eventually ovum is transported into the ampulla of fallopian tube.
After ovulation blood is filled in graffian follicle & now it is known as corpus haemorrhagium.
(D). Secretary Phase
It is a last phase of M.C which is occurs from 15-28th day of M.C. During this phase the secretion of estrogen and progesterone hormone is increased very much so it is known as secretary phase. Now the corpus haemorrhagium is converted in a yellow coloured structure is known as corpus luteum. The corpus luteum does starts secretion of estrogen and progesterone hormone in high quantity.
As a response of estrogen and progesterone hormone the thickness of endometrium keeps increasing & it becomes 8 mm on 28 day of M.C.
• Now if pregnancy occurs then corpus luteum keeps the secretion of estrogen and progesterone till 3 months of pregnancy & M.C is stopped.
• Now if pregnancy does not occur, then corpus luteum is converted in white coloured non- functional structure known as 'corpus albicans '. Hence secretion of estrogen and progesterone hormone is stopped on 28th day the level of estrogen and progesterone hormone is lowest while as thickness of endometrium is 8 mm.
• Now in the absence of estrogen and progesterone hormone thr endometrial tissue starts dying & it comes out again as menstrual discharge.
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