<unk>  is a phase of the menstrual cycle in which the uterine lining (endometrium) is shed. Menstrual cycles occur exclusively in humans and other great apes. The females of other mammalian species experience an estrus, in which the endometrium is reabsorbed by the animal at the end of its reproductive cycle.
Menstruation
Pronation
Oviparity
Menopause
Ejaculation
Secondary amenorrhea
Primary amenorrhea
Menstrual cycle