The female reproductive cycle is composed of several hormonal activities, among which menstruation is the primary one. The menstruation cycle repeats typically at an interval of 28-30 days wherein the female body prepares itself for a potential pregnancy.
Menstruation is a periodic shedding of the uterine lining. It occurs in three phases, namely the follicular phase, the ovulatory phase, and the luteal phase and is governed by four major hormones- follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone.
It is the first phase of the menstrual cycle and starts on the first day of the period. A series of events occur during the follicular phase, wherein different hormones play significant roles. The phase initiates at the brain, which releases FSH and LH that travel in the blood to the ovaries and stimulate the growth of eggs.
At the same time, growing eggs release a female hormone, estrogen. When the level of estrogen rises and reaches a certain point, the production of FSH decreases. This hormonal balance maintains the number of follicles that mature. Out of many follicles, one follicle in one of the ovaries continues to mature and becomes dominant. Eventually, the growth of other follicles suppresses, and gradually they die. The dominant follicle continues producing estrogen.
It is the second, and the most important phase of the menstrual cycle wherein ovulation occurs, and the chances of conception are high. In this phase, the level of estrogen is at its peak and triggers an increase in the amount of LH. These hormonal upsurges cause the dominant follicle to release its egg from the ovary, and the process is called OVULATION.
The released egg is captured by finger-like projections, fimbriae present at the end of the fallopian tube that ultimately sweeps it inside the tube. The cervix produces mucus that increases in amount and thickness during the ovulatory phase. When women have intercourse during this phase, the thick mucus captures the sperm and helps it to move towards the egg. It leads to the fertilization of egg and sperm that result in conception.
It is the last phase of the menstrual cycle and starts right after the ovulation. As soon, the follicle releases the egg; it develops into a new structure called corpus luteum. It secretes another hormone of the female reproductive cycle, progesterone. The function of progesterone is to prepare the uterus to implant the fertilized egg.
If fertilization has taken place during the intercourse, the fertilized egg, also called embryo, will travel through the fallopian tube to implant in the uterus. The woman is now considered pregnant. However, if the egg is not fertilized, it gets disintegrated. Since pregnancy does not occur, the uterus lining breaks down and sheds in the form of blood that consists of old parts of uterine tissue, cells from the mucous lining of the vagina, and bacteria making up the vaginal flora.
