Estrous cycle, oestrous cycle,menstural cycle

Estrous cycle OR oestrous cycle
The estrous cycle or oestrus cycle (derived from Latin oestrus 'frenzy', originally from Greek οἶστρος oîstros 'gadfly') is the recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phases or by pregnancies. Typically, estrous cycles continue until death. Some animals may display bloody vaginal discharge, often mistaken for menstruation.

Menstrual cycle
The menstrual cycle is the regular natural change that occurs in the female reproductive system (specifically the uterus and ovaries) that makes pregnancy possible.[1][2] The cycle is required for the production of ovocytes, and for the preparation of the uterus for pregnancy.[1] Up to 80% of women report having some symptoms during the one to two weeks prior to menstruation.[3] Common symptoms include acne, tender breasts, bloating, feeling tired, irritability and mood changes.[4] These symptoms interfere with normal life and therefore qualify as premenstrual syndrome in 20 to 30% of women. In 3 to 8%, they are severe.[3]
The first period usually begins between twelve and fifteen years of age, a point in time known as menarche.[5] They may occasionally start as early as eight, and this onset may still be normal.[6] The average age of the first period is generally later in the developing world and earlier in developed world. The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women and 21 to 35 days in adults (an average of 28 days).[6][7] Menstruation stops occurring after menopause which usually occurs between 45 and 55 years of age.[8] Bleeding usually lasts around 2 to 7 days.[6]