CBSE Class 10 Answered

Animals that have estrous cycles reabsorb the endometrium (inner membrane of the mammalian uterus) if conception does not occur during that cycle. In menstrual cycle, the endometrium is shed through menstruation when pregnancy does not occur.

In oestrous cycle, the female is fertile and sexually receptive during the estrous phase whereas in menstrual cycle, the female may be sexually receptive at any time during the cycle.

The estrous cycle allows the animals to place most of their mating energy into particular periods, and generally it is obvious to the males when females are in estrous. In contrast, the menstrual cycle of human beings, allows sexual activity at any time and without overt external signs to signal estrual receptivity

In Oestrus cycle, the interval between two successive cycles varies between a few months to over a year. In menstrual cycle, the interval between two successive cycles is about 4 weeks