Question

Differentiate between the menstrual cycle and the oestrus cycle.

Answer 1

Hint: A cycle of certain days runs in any birth-giving mammal. This cycle is to ensure and prepare the female body for holding the child during pregnancy. It starts from a certain age and continues till menopause. This process makes a body adjustable for giving birth to a new offspring.

Complete answer:
The menstrual cycle is a cycle that involves the growth of the female uterus. Shedding of endometrium via blood if the sperm and egg are not fertilized.
This endometrium supports the foetus if implanted.
Unlike in the oestrous cycle, the endometrium is reabsorbed by the walls of the uterus if the fertilization does not take place. This process continues until death.

Let us see some differences between the two cycles.

Menstrual Cycle	Oestrous cycle
It occurs in primates.	It occurs in non-primates.
The menstrual cycle has proliferative, secretory and menstrual phases.	It does not have any of these phases.
It is very complex.	It is less complex
Sexual receptivity may occur throughout the menstrual cycle.	Sexual receptivity occurs usually in between the oestrous cycle.
The endometrium shed is expelled through the blood.	The endometrium shed is absorbed by the walls of the uterus.
For example- humans, apes etc.	For example- cow, dog etc.

Note: The oestrous cycle in cows is for 21 days whereas the menstrual cycle in humans is for 28 days. There are 4 phases in the estrus –proestrus, estrus, metestrus and anestrus. The oestrous cycle usually is followed till the death but the menstrual cycle ceases after 45 -50 years of age.