Answer:
Menstrual Cycle:-
(1) Menstruation occurs in human, apes and old world monkeys.
(2) Menstruation is bleeding from the uterus of adult females at intervals of one lunar month.
(3) Beginning of menstruation or first menstruation is called menarche.
(4) The beginning of menstruation varies. It usually occurs between 12 and 15 years.
(5) The cycle of events starting from one menstruation till the next one is called Menstrual Cycle.
(6) In human females, menstruation is repeated at an average interval of about 28/29 days.
(7) One ovum is released (ovulation) during the middle of each menstrual cycle.
(8) It is regulated by certain hormones, some of which are secreted by the pituitary gland.
(9) The pituitary gland is stimulated by releasing factors produced in the hypothalamus.
(10) The hormones produced by the pituitary gland influence the ovaries. The hormones secreted by the ovaries affect the walls of the uterus.