For species that rely on sexual reproduction, including mice and men, offspring can only happen if sperm from the male fertilize eggs from the female. Even artificial fertilization techniques depend ...

Semen is a fluid that carries sperm, or male reproductive cells, out of the body during ejaculation. The average amount of ...

For decades, sperm were thought to become fully active the moment they entered the female reproductive tract. New research suggests otherwise. A temperature-sensitive switch inside sperm cells may ...

A man in his early 20s received a transplant of his own sperm-producing stem cells, which had been frozen since his childhood, in an attempt to regain fertility. Doctors are waiting to see if the ...