Observe the diagram of menstrual cycle and answer the following questions:
(1) What is the period of menstruation?
(2) On which day does ovulation occur during menstrual cycle?
(3) During which period is corpus luteum active during menstrual cycle? Which hormones are secreted by corpus luteum ?
(4) In menstrual cycle which reproductive organs undergo changes?
(5) Which period is said to be period of regeneration of endometrium?
(6) Which period is said to be period of secretions of glands in the endometrium?