In the female reproductive system, it is important to distinguish between two related but clearly distinct pathways.
On the one hand, the uterus or endometrial cycle where the endometrium grows during the menstrual cycle while waiting for fertilization to take place and the embryo to implant. If this does not happen, the endometrium sheds in the form of bleeding, which is what is known as menstruation. Once menstruation is over, the endometrium grows back.
On the other hand, there is the ovary and the ovulatory cycle. Here, the ovarian follicles mature and only one, the dominant follicle, will reach the final stage and be released.
Normally, ovulation and menstruation do not coincide in time, although there are cases in which the coincidence can occur, especially in short cycles.