Question

Describe the menstrual cycle in human females and add a note on its hormonal control?

Answer 1

• The monthly development and shedding of the functional layer of the uterus are called the menstrual phase and the maturation of an egg (every month) and its release is called the ovarian cycle.
• Together these two cycles are called the menstrual cycle.
• Phases of the menstrual cycle :

1) Menstrual phase - In this phase, there occurs the discharge of blood cells and unfertilized ovum from endometrium of the uterus which lasts for 3-5 days.

• During this phase, progesterone and estrogen hormone level get decreased.
  

2) Proliferative phase - In this phase, the FSH stimulates the ovarian follicles to secrete estrogen.

• Estrogen maintains the female reproductive structures such as ovarian follicles as well as the lining of the uterus.
  
• During the second week of the reproductive cycle, most of the developing follicles die and only one follicle continues to mature.
• The LH surge during this phase causes the ovulation (the release of an immature egg between 10- 14days).
  

3) Secretary phase- In this phase, the egg (after ovulation) reaches the uterus.

• It begins to enlarge and forms a yellowish structure called corpus luteum.
• The corpus luteum plays an important role in the preparation of the endometrium for the implantation of the fertilized egg by secreting estrogen and progesterone.
• If the egg is not fertilized, then the corpus luteum begins to degenerate.
• The production of progesterone and estrogen hormones decreases which leads to the shedding of the lining of the uterine endometrium.