In primate female(ape, monkey, human) this is a normally 28 days cyclical period in which there is shedding off of endometrium lining followed by their proliferation.
There is Changes in uterine wall and ovarian follicle.
The first menstruation is called menarch which generally starts at the age of 12 to 13 years, before this there is about 4 to 6 lakhs of ovarian follicles present in the ovary. The last menstruation is called menopause (at the age of 45 to 48 years)
Menarch—*reproductive phase*—- menopause
During reproductive please the cycle occurs and during this cycle one graffian follicle matures at a time.
Phases of MENSTRUAL CYCLE
1. Bleeding phase/Menstruation phase(1-5 days).
2. follicular phase/Proliferation phase/preovulatory phase/Estrogenic phase(6-14 days).
3. Ovulatory phase(14th day).
4. Luteal phase/progesteronic phase(15-28days).
The hormonal pathway of control is as in the following picture:-
