If egg has no fertilization, no egg implants, and uterus internal lining sloughs off {menstruation}| {menses}. Menstrual bleeding is greater in women than in other primates.
In most sexual animals, females have periods {estrus}| {heat, sex} {sexual readiness} {estrous cycle} when they are receptive to males, during which uterine glands secrete.
First-menstruation age {menarche}| is from 14 to 19 years old and decreases with city life, high-protein diet, and more exposure to males.
Menstruation typically ceases {menopause}| at 40 to 45 years old.
Females can have regular sex-receptive periods {rut, sex}|.
4-Zoology-Organ-Reproduction-Female
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Date Modified: 2022.0225