Question

Ovulation occurs in which of the following stages of an estrous cycle?

• A. Proestrus
• B. Estrus
• C. Metestrus
• D. All of the above

Answer 1

Answer: (B)

Estrus

The reproductive cycle of the non primate females is called estrous cycle. For example, in rats, horse etc. It can be divided into four phases proestrus, estrus, metestrus and diestrus. Proestrus stage is the building up phase. The ovarian follicle becomes large and secretes estrogen which is necessary for the preparation of estrus and pregnancy. Estrus is the phase when ovulation takes place. It is also known as the period of heat and female is sexually receptive. Metestrus is the phase where corpus luteum forms under the influence of decreased estrogen and increased progesterone level. Diestrus is the phase where corpus luteum becomes functional and the progesterone level increases. So, the correct option is B.