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

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 ...

Rat sperm cells generated from stem cells in the lab have been used to produce fertile offspring for the first time. The approach could be adapted to rescue endangered rodents and may help to inform ...

Mice are the envy of the genetics world thanks to the ease with which these animals can be genetically altered by tinkering with cultured embryonic stem (ES) cells. When it comes to making straight ...