The cyclical disembogument of blood, mucus and certain other substances from the uterus in the reproductive life of female at an average interval of 28 days.
It materializes from puberty to menopause.
It is absent before puberty, during pregnancy and after menopause that is at the age of 45-50 years.
The flow continues for 4-6 days without any substantial pain.
It is concocted of blood which may be 30-40 ml, deprived endometrium, mucus, leucocytes and unfertilized ovum.
The menstrual blood which oozes out from the uterus clots instantaneously due to brisk formation of fibrin.
If the blood prevails in the uterus, fibrin is sublimated on the endometrium and as a result there is fragmentary clotting.
Intra-uterine clots if preserved for a prolonged time deliquesce due to the exertion of plasmin.
Throughout each cycle uterine mucosa gradually hypertrophies.
The unabridged intention is to assemble a convenient bed for the reception and implantation of the fertilized ovum.
If pregnancy takes place the proliferated mucosa gets metamorphosed into placenta.
If pregnancy does not befall, the hypertrophied mucosa seizes down and is voided as menstruation.
Menstruation, therefore, may be designated as 'funeral of unfertilized ovum' or the 'weeping of the uterus for the lost ovum'.
Menstruation has four junctures: 1.
Resting of Follicular Phase 2.
Proliferative Phase 3.
Premenstrual or Luteal Phase 4.
Destructive or Menstrual Phase a.
Resting or Follicular Phase Its duration is of 1-5 days.
The endometrium mends and becomes normal.
Decelerate proliferative changes occur.
Corpus luteum has wretched.
Inhibitory action of progesterone is absent, hence, follicles ploddingly maturing and the oestrogen secretion looming.
Urine contains oestriol and oestrone whose level climbs up later on.
The proliferative changes are due the consequence of oestrogens from the maturing follicles whose secretion is controlled by the follicle stimulating hormone of anterior pituitary.
b.
Proliferative Phase Its duration is of 6-14 days i.
e.
, until ovulation.
During this phase the mucosa congeals and becomes more vascular.
Endometrial glands become extended, tortuous, narrow and straight.
Vessels rather dilate, the end of the secretory vacuoles manifest underneath the nuclei of glandular cells.
During this phase the Graafian follicles start maturing and the oestrogen secretion increases.
On the 14th day ovulation springs up and the formation of corpus luteum starts.
The urine has maximum content of oestrogen.
Injection of oestrogen in the ovariectomized animals fabricates same changes.
This phase is controlled by the follicular stimulating hormone of anterior pituitary which is finally inhibited by high oestrogen level.
c.
Premenstrual or Luteal Phase Its duration is of 15-28 days.
The mucosa intricates further, glands become more augmented and inflated with mucus, capillaries dilated like sinus, trickling of clear or blood stained fluid.
Proliferation of stroma cells, secretory vacuoles accommodating glycogen emerge above the nuclei.
Progesterone secreted inhibits further maturation of the follicles.
Corpus luteum grasps maximum size on the 19th day and its growth continues till the 27th day and then degenerates on the 28th day.
Urine has pregnanediol which appears 2-3 days after ovulation and soars to maximum about one week before the period and falls 2-3 days before the flow starts.
Oestrogen level falls.
Formation of corpus luteum and secretion of progesterone is controlled by leutinizing hormone and the leutotrophic hormone of the anterior pituitary.
Voiding of the menstrual fluid is aided by the presence of certain prostaglandins.
d.
Destructive or Menstrual Phase It starts on the 28th day.
Its duration is of 4-6 days.
During this phase capillaries rift and haemorrhage occurs.
Superficial endometrium with pseudodecidual stroma and tortuous glands are sloughed off but the basal layer lingers unscathed.
Corpus luteum degenerates because the placental gonadotropins which are essential for the growth of corpus luteum are absent.
In absence of pregnancy no placenta forms hence, corpus luteum degenerates.
Lack of progesterone is also responsible for menstrual flow.
Oestrogen level is at minimum during menstruation and escalates during follicular phase.
After ovulation it falls to a plateau.
Progesterone output appears to be at low level during the follicular phase.
It commences just before tthe ovulation and reaches zenith soon afterwards thereafter declining until the next menstrual bleed.
In normal menstrual cycle there is a shatter of lutenizing hormone during the time of ovulation.
Thus, it can be convicted that the process of menstruation is very essential for a number of life process to take place in the body of a female.