Oestrus is also the biological genus name of the gadfly. The estrous cycle (also oestrous cycle; originally derived from Latin oestrus) comprises the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females. Humans undergo a menstrual cycle instead. Estrous cycles start after puberty in sexually mature females and are interrupted by anestrous phases. Typically estrous cycles continue until death. Some animals may display bloody vaginal discharge, often mistaken for menstruation. Differences from the menstrual cycle Mammals share the same reproductive system, including the regulatory hypothalamic system that releases gonadotropin releasing hormone in pulses, the pituitary that secretes follicle stimulating hormone and luteinizing hormone, and the ovary itself releases sex hormones