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

The correct option is B The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles

Menstrual cycle occurs in primates (monkeys, apes and human beings). This cycle consists of the menstrual phase, the proliferative phase and the secretory phase and the broken endometrium is passed out during menstruation. The oestrous cycle occurs in non-primates such as cows, dogs, etc. It consists of a short period of estrus or heat followed by anoestrus or passive period. The broken endometrium is reabsorbed during the oestrous cycle.

So the correct option is 'the endometrial lining is shed in menstrual cycles but reabsorbed in the oestrous cycle'.