1.6 F The Menstrual Cycle (M.C.), the purpose :

Preadolescent girls often wonder exactly what a "normal" period will be. Physical development and menstrual cycle are controlled by the delicate balance of hormones. Stimulated by hormones from the pituitary gland, the ovaries produce the hormone ESTROGEN, which plays a major role in stimulating the physical changes of puberty, including the onset of menstruation. A second hormone, PROGESTERONE, is produced by the ovaries when ovulation occurs.

From beginning of menstruation between 11 to 14 years(Menarche) to cessation of menstruation between 40 to 45 years(MENOPAUSE), the rhythmic patterns of the female cycle are controlled by these hormones. Each time a girl gets her period, a new cycle begins. The cycle usually lasts about 28 days, but the length of the cycle varies from 21 days to 40 days. The menstrual cycle(M.C.) is explained as under:

1) The menstrual phase : The dissolved endometrium lining of the uterus & unfertilized ova comes out of the body through vaginal opening as menstrual flow.
2) The pre - ovulatory phase : The lining of the uterus starts building up again and one of the ovaries is getting ready to release the another ova. The blood lining of the uterus gradually thickens prior to ovulation.
3) The Ovulation phase : It is the event when one of the two ovaries releases an ovum (egg cell) into the nearby fallopian tube.
4) The post-ovulatory phase : The ova travels through the fallopian tube into the uterus. The lining of the uterus continues to thicken with blood and nutrient tissue.

Ovulation generally occurs about 14 days before the onset of the next period, which is the probable time to get pregnant, although this may vary with each individual and each new cycle. Usually only one ova is released, but occasionally two or more may be released. The ovaries begin producing the hormone progesterone, which causes the lining of the uterus to become thick with blood and tissue, just after ovulation.