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

During pregnancy, corpus luteum releases a large amount of progesterone and oestrogen due to the neural signal given by the maternal endometrium to the hypothalamus.

This sustains the release of Luteinising hormone and maintains the embryo until the gestation period. If the fertilisation does not occur, corpus luteum would not be able to remain active for more than 10-12 days because of the lack of progesterone which is required to maintain the corpus luteum.