Question

A difference between estrous and menstrual cycles is that
A. Non-mammalian vertebrates have estrous cycles, whereas mammals have menstrual cycles
B. The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles
C. Estrous cycles occur more frequently than menstrual cycles do
D. Ovulation occurs before the endometrium thickens in estrous cycles

Answer 1

Hint: In every birth-giving mammal, a series of unique days runs. This cycle is intended to ensure and prepare the female body during pregnancy for carrying the infant. This begins at a certain age and lasts until menopause. This approach allows an adjustable body to give birth to a new offspring.

Complete answer:The menstrual cycle is a cycle involving female uterus development. Shedding of the endometrium by blood if there is no fertilization of the sperm and egg. The endometrium is reabsorbed by the walls of the uterus in the oestrous cycle if fertilization does not take place. Until death, this process continues.

Menstrual cycle	Oestrous cycle
In this continuous breeders are observed.	Seasonal breeders are observed.
It causes blood loss.	Blood loss is not associated with this Cycle.
Keeps working till menopause.	Continual until death.
Examples: monkeys and humans.	Examples: Cows and dogs.

In primates, the menstrual cycle is (monkeys, apes, and human beings). This period consists of the menstrual process, the proliferative phase, and the secretory phase, and during menstruation, the broken endometrium is passed out. In non-primates such as cows, pigs, dogs, etc the oestrous cycle occurs. It consists of a brief period of oestrus or heat accompanied by a passive period of anoestrus. During the oestrous cycle, the broken endometrium is reabsorbed.
So, B-The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles, is the correct choice.

Note: In cows, the oestrous cycle lasts 21 days, and in humans, the menstrual cycle lasts 28 days. In the estrus, there are 4 stages: proestrus, estrus, metestrus, and anestrus. The oestrous cycle is usually followed before death, but after 45-50 years of age, the menstrual cycle ends.