Menstrual Cycle: Tears of Uterus

In a life cycle, a woman’s body is vulnerable to a variety of changes. The cycle of these changes in women every month, positively for pregnancy is called menstrual cycle. When an ovum is unfertilized, the uterus lining sheds and leads to hemorrhage, called menstruation. In a girl, menstruation starts from the age of 10 to 15 when she attains puberty and this beginning is known as menarche. The ending of menstruation is known as menopause which takes place at the age range of 50.

The first day of bleeding is marked as the first day of a menstrual cycle and period from one menstrual cycle to another can vary from 28 to 30 days.

Before discussing the different phases of menstrual cycle, it is important to have a glimpse of female reproductive system and organs involved in this cycle. They mainly include:

  • A pair of ovaries which stores, nourishes and releases ova.
  • Uterus (womb), where implantation of a fertilized egg takes place and the fetus develops.
  • Pair of the fallopian tube connecting the ovaries and uterus.

The count of the ovum in each ovary is decided and fixed before the birth of a girl. As she reaches puberty, hormones stimulate the development and release of one ovum per month. This continues till menopause.

Phases of menstrual cycle

The menstrual cycle is divided into four phases, namely:

  1. Menstrual phase: Day 1, uterus lining which is prepared for implantation starts to shed which lasts 3 to 5 days.
  2. Follicular phase: A matured egg follicle releases an egg from one of the ovaries. Also, uterus starts preparation for another pregnancy.
  3. Ovulatory phase: Mid-cycle phase, this is the phase in which ovulation takes place i.e., day 13-17. End of follicular phase along with ovulation period defines the fertilization period.
  4. Luteal phase: Post ovulation phase where the fate of corpus luteum is decided. If fertilization occurs, pregnancy starts. If fertilization doesn’t occur, it marks the onset of another cycle.

Menstrual cycle

Menstrual Hormones

The chemical messengers in our body called hormones, released by various endocrine glands are responsible for many changes in a human body. Menstruation is a slave to certain hormones. Every phase of the menstrual cycle is influenced by a female hormones namely estrogen, progesterone, FSH and LH. The variation in the level of each of these hormones decides the phase which a girl undergoes.

We had an overview of the menstrual cycle. For detailed information, download Byju’s-The Learning App.


Practise This Question

During spermatogenesis which of the following is the first cell to become haploid?