Onset of menstruation is due to

The corpus luteum in pregnancy has a long life. However,if fertilization does not take place,it remains active only for $10-12$ days. Explain.

The corpus luteum formed during the post-ovulatory phase of the menstrual cycle survives for only . . . . . . weeks in the absence of fertilization.

When is the menstrual cycle not observed?

Which hormone level is required for ovulation in females?

The menstrual cycle is regulated by which of the following?