Describe menstrual cycle

The reproductive cycle starting from the one menstruation till the next one in the female primates is called menstrual cycle. The first menstruation which begins at puberty and is called menarche . The cycle is repeated at an interval of 28-29 days. Menstrual cycle involve three phases- menstrual phase, follicular phase and luteal phase.

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.