Each normal cycle in women usually lasts 28 days and is controlled by hormones secreted by glands in the brain (hypothalamus, pituitary) and ovaries. The purpose of these hormones is to stimulate the ovaries to release an egg and create the proper environment in the uterus to implant the embryo and achieve pregnancy. Significant fluctuations can be seen in the number of days in the cycle, so that stable cycles of 22-40 days are considered normal.
Women are born with approximately 3,000,000 follicles, during puberty, the number of follicles decreases to 400,000 and only 400 of them produce eggs capable of fertilization throughout the woman’s reproductive age.
At the beginning of menses, only one follicle begins to mature under the effect of follicle-producing hormone (FSH) that is infiltrated by the pituitary gland. As this grows, it produces estrogen and when it reaches near maturity (towards the 12th day on a 28-day cycle) stimulates the production of another luteinizing hormone (LH), which helps the follicle mature and release the ovum-ovulation (towards 14th day on a 28-day cycle). Ovulation occurs 34-36 hours after the LH tip. Immediately after his release, the egg is retained by the fallopian tubes where the egg meets spermatozoa, i.e. fertilization takes place (A1).
After ovulation, the empty follicle is converted into a bladder form called a corpus luteum, which produces hormones such as progesterone, which together with estrogen matures the endometrium, that is, the inner wall of the uterus to implant the fertilized egg-embryo. Immediately after ovulation, the onset of a hormone called progesterone starts, the rise of which rises 7 days after ovulation. If the egg is not fertilized, progesterone drops and its prolonged fall causes apoptosis of the endometrium (menstruation – period) 14 days after ovulation.