Read the graph given above and correlate the uterine events that take place according to the hormonal levels on
(i) 6 - 15 days
(ii) 16 - 25 days
(iii) 26 - 28 days (if the ovum is not fertilised )
(b) Specify the sources of the hormones mentioned in the graph.

Explanation

(i)Regeneration of endometrium and ovulation
(ii) Uterus gets highly vascularised, spongy and is ready for embryo implantation
(iii) If ovum is not fertilised the endometrium disintegrates leading to menstruation