menstrual cycle

The menstrual cycle is a natural, monthly process that occurs in females of reproductive age. It involves a series of hormonal and physiological changes in the female reproductive system. Here’s an overview of the menstrual cycle:

1. Menstrual Phase (Days 1-5):

The menstrual cycle begins with the onset of menstruation (period).

During this phase, the inner lining of the uterus, called the endometrium, sheds. This shedding results in the discharge of blood and tissue from the uterus through the vagina.

The menstrual flow typically lasts for about 3 to 7 days.

2. Follicular Phase (Days 1-13):

Concurrently with the menstrual phase, the brain’s pituitary gland releases follicle-stimulating hormone (FSH).

FSH stimulates the ovaries to develop several ovarian follicles, each containing an immature egg (oocyte).

Usually, only one dominant follicle continues to develop, while the others degenerate.

The dominant follicle matures and produces estrogen.

3. Ovulatory Phase (Day 14):

A surge in luteinizing hormone (LH) from the pituitary gland triggers ovulation.

Ovulation is the release of the mature egg from the dominant follicle into the fallopian tube. It usually occurs around the middle of the menstrual cycle.

This is the most fertile phase of the menstrual cycle, and it lasts for about 24 hours.

4. Luteal Phase (Days 15-28):

After ovulation, the ruptured follicle transforms into the corpus luteum, a temporary endocrine structure that secretes progesterone.

Progesterone prepares the uterine lining (endometrium) for potential embryo implantation.

If fertilization and implantation do not occur, the corpus luteum breaks down, leading to a drop in progesterone and estrogen levels.

This hormonal shift triggers the start of menstruation, and a new menstrual cycle begins.

5. Hormonal Regulation:

The menstrual cycle is tightly regulated by the interplay of hormones, primarily FSH, LH, estrogen, and progesterone.

Estrogen and progesterone play key roles in preparing the endometrium for pregnancy.

6. Average Cycle Length: The menstrual cycle typically lasts around 28 days, although it can vary from person to person. Cycles ranging from 21 to 35 days are considered normal.

7. Menstruation and Fertility: Menstruation is a sign that the female reproductive system is healthy and functioning correctly. It also marks the start of a new cycle, during which conception can occur if sexual intercourse takes place during the fertile window around ovulation.