Menstrual cycle

Menstrual cycle is a phenomen which  consists in the the beginning of the sexual cycle in women. During this stage there are several modifications in the women's body, such as the set up of the uterus, the oogenesis. There is also a change in the endocrine system in order to prepare the coming of an potential embryo. 

It lasts around 28 days but obviously this duration is different for every women.