A type of ovulation cycle where the endometrium is shed if pregnancy does not occur.

Period from onset of one menstrual bleeding to the next in an ovulating woman or female primate.

The Menstrual Cycle involves regularly recurring hormonal changes and physiologic endometrial changes during the reproductive period in human females, and some primates, and culminates in partial sloughing of the endometrium (menstruation) in the absence of fertilization. For most women, one cycle takes 28 days. (NCI)

The monthly cycle of hormonal changes from the beginning of one menstrual period to the beginning of the next.

The period from onset of one menstrual bleeding (MENSTRUATION) to the next in an ovulating woman or female primate. The menstrual cycle is regulated by endocrine interactions of the HYPOTHALAMUS; the PITUITARY GLAND; the ovaries; and the genital tract. The menstrual cycle is divided by OVULATION into two phases. Based on the endocrine status of the OVARY, there is a FOLLICULAR PHASE and a LUTEAL PHASE. Based on the response in the ENDOMETRIUM, the menstrual cycle is divided into a proliferative and a secretory phase.

Menstruation is the shedding of the lining of the uterus (endometrium) accompanied by bleeding. It occurs in approximately monthly cycles throughout a woman's reproductive life, except during pregnancy. Menstruation starts during puberty (at menarche) and stops permanently at menopause.