How do behavior, morphology and physiology act in concert to improve a male's reproductive success - and why is there so much variation among outcomes within and between species? Aa Aa Aa ...

The vagina, or birth canal, connects the cervix to the outside of the body. In male reproductive organs, the scrotum holds the testes, which produce sperm and sex hormones, including testosterone.

The female reproductive system includes internal and external organs, each designed to carry out varying functions. Learn ...

While most animals reproduce sexually, some species rely solely on females for parthenogenetic reproduction. Even in these ...