Menstruation

Menstruation, the periodic monthly discharge of the inner lining of the uterus (endometrium), lasts about 4 to 5 days and occurs, on the average, every 28 days. During this period, known as the menstrual cycle, an egg cell (oocyte) matures and is ovulated. The uterus at this time prepares a suitable environment in which a fertilized egg could develop into a fetus.

Phases of the Cycle

The first day of menses, or the onset of menstrual flow, is considered the first day of the cycle. Although 28 days is considered an average cycle, the time may range from 21 to 35 days. Climate, emotional factors, age and drugs or medicine can alter the length of the menstrual cycle.

Days 0 to 13 of the cycle are called the follicular phase. Women are born with about 2 million ovarian follicles, microscopic structures, each of which surrounds an egg. At the start of a menstrual cycle about 200 follicles enlarge and become filled with fluid. By day 5 or the cycle, one of them begins to grow, while the others disintegrate. At midcycle, day 14, the oocyte within this follicles matures, the follicle ruptures, and fallopian tube. This condition is theoretical that normally happen to women. If any sexual relationship on the follicular phase theoretically will no fertilization by sperm to egg cell, because the cell egg is not mature yet.

During the luteal phase, from day 14 to 28, the collapse follicle transforms into a corpus luteum and secretes progesterone, where progesterone is reproduction hormone that control of every women uterus activity.