Question

Short / Long Answer question Type :
Describe various phases of menstrual cycle emphasizing the role of hormones. What is the period when there is maximum chance of conception?

Answer 1

1. Menstruation - Menstruation is the elimination of the thickened lining of the uterus (endometrium) from the body through the vagina. The menstrual fluid contains blood, cells from the lining of the uterus and mucus. The average length of this period is between 3 - 6 days.

2. Follicular phase - The follicular phase starts on the 1st day of menstruation and ends with ovulation. Stimulated by the hypothalamus, the pituitary gland releases follicle stimulating hormone (FSH). This hormone stimulates the ovary to produce around five to 20 follicles. Each follicle houses an immature egg. Only one follicle out of these follicles will mature into an egg, while the others die. This can occur around the 10th day of a 28-day cycle. The growth of the follicles stimulates the lining of the uterus to thicken in preparation for pregnancy (if any).

3.. Ovulatory phase - It refers to the release of the ovum from the ovary. This usually occurs mid-cycle i.e. on the 14th day of the menstrual cycle. During the follicular phase, the developing follicle causes a rise in the level of estrogen. The hypothalamus in the brain recognizes these rising levels and releases a chemical called gonadotrophin-releasing hormone (GnRH). This hormone prompts the pituitary gland to produce raised levels of luteinizing hormone (LH) and FSH. Within two days, ovulation is triggered by high levels of LH. The egg is funneled into the fallopian tube and toward the uterus by waves of small, hair-like projections. The life span of the typical egg is only around 24 hours. Unless the ovum gets fertilized by the sperm during this time, it will die.

4. Secretory phase or Luteal phase - After the ovulation, the luteal phase starts. In this, the follicular cells and the cells of zona granulosa of a ruptured follicle form a yellow glandular structure known as Corpus luteum. Its main function is to secrete a different kind of female sex hormone termed as Luteal hormone (Progesterone). Progesterone prepares the uterus for implantation of the fertilized ovum to establish a pregnancy. It thickens the endometrium of the uterus, increases blood supply, the fat, and glycogen, contents of the endometrium cells. Thus we can see that there's an increase in the level of progesterone in the luteal phase.