1.   In general, all female mammals are cyclic, but only some are seasonal.

2.   Only a small proportion of the millions of eggs with which a female mammal is born mature and are released at ovulation.

3.   In principle, female mammals, even humans, should be able reproduce without sex.

4.   On her rear end she sported the small, bright pink swelling characteristic of the early stages of estrus, the period when female mammals are sexually receptive.

5.   He also discovered that one of the two X-chromosomes in female mammals is inactive.