MENSTRUAL CYCLE:

 MENSTRUAL CYCLE: The gametes formation in females takes about 28 days( it varies from female to female but average taken to be 28 days).In this cycle, rhythmic changes occur in the reproductive organ of female primates ( Monkeys, apes and human being). The first menstruation begins at puberty   ( on set of reproductive phase, in female it generally starts from the age of 12 years) and it is called menarche. Human female's fertility period extend from around 12 years to Menopause at about 45 - 50 years. Menopause is the term given when in woman's life ovulation and menstruation stops. During the reproductive period say from around 12 years to around 45 - 50 years , generally one egg is released every 28 days or so alternately from two ovaries. In female there is the occurrence of one pair of ovary - right and left ovary. Suppose if in the first  menstrual cycle, right ovary produces the egg than left ovary at that moment remains silent and in the next  menstrual cycle left ovary will release the egg where as the right ovary remains silent. Generally female remain fertile for around 32 years and about 13 eggs mature each year.

The menstrual cycle in human being lasts 28 days. The days are numbered from the first day of the blood flow in the menstrual period. So these cycle events from the first day is called the Menstrual cycle The menstrual cycle in humane female is divided into three phases: 

 1)Follicular or Proliferating Phase 

 2)Luteal or Secretory Phase

 3)Menstrual or Bleeding Phase

In all these above phases Endometrium layer lining the uterus develops, Huge number of hormone secretion occurs, Ovary becomes ready to release an  egg and if the egg is not fertilised then the endometrium starts breaking down.