Apoptosis can occur by change in hormone levels in the ovarian cycle. When there is no feilization of the ovum, the endometrial cells die because :

Ans. is a i.e. The involutlon of corpus luteum causea estradlol and progesterone levels to fall dramatlcally "The withdrawl of estrogen and progesterone initiates impoant endometrial events, vasoconstriction, the process of apoptosis, fissue loss and tinally menstruation." In the first half of the secretory phase, acid phosphatase and potent lytic enzymes are confined to lysosomes. Their release is inhibited by progesterone stabilisation of the lysosomal membranes. With the involution of corpus luteum, levels of estrogen and progesterone fall, the lysosomalmembranes are not maintained and enzymes are released which cause apoptosis of the endometrial cells.