The menstrual cycle can be examined in three phases;
1. Follicular phase: Begins with the first day of menstrual bleeding. Growth occurs in follicles under the influence of FSH (follicle stimulating hormone), which is secreted from the pituitary gland located under the brain and stimulates the development of follicles (the structure containing fluid, egg cells and cells surrounding the egg) in the ovaries. After a while, the secreted FSH level drops slightly, so only one of the growing follicles in a group stands out and forms the mature egg that month. Other follicles degenerate and disappear, never to be used again. This developing follicle, in addition to creating an egg, also produces the hormone estrogen during this period, thanks to the other cells it contains. This hormone plays a role in many important steps in pregnancy, such as the thickening of the uterine lining and the formation of transparent fluid discharge from the cervix.
2. Ovulation phase: It is a short period of time. In a dramatic response to increased estrogen hormone, LH (luteinizing) hormone levels rapidly rise. This LH surge allows the egg to complete its final maturity division and expel the egg from the follicle. This event usually occurs 14 days before the next menstrual bleeding.
3. Luteal phase: Begins with ovulation. The follicle from which the egg is expelled changes to produce progesterone hormone along with estrogen and forms the yellow body (corpus luteum). This hormone is very important because it transforms the lining of the uterus into a suitable place for the fertilized egg to attach. If pregnancy occurs, hormone production begins and the yellow body is not stimulated, its function ends 12 - 1
4 days after its formation. Therefore, progesterone hormone levels decrease, the uterine lining is shed and excreted through bleeding.
Read: 0
