Reproductive System

A mesmerizing 6-minute time lapse shows a single cell dividing seemingly endlessly until what was once a yellow blob has become a wriggling, darting salamander tadpole.

The findings contradict previous research, but they are far from conclusive.

Mice with two dads are harder to make than mice with two moms.

Men's testes were once thought to be free of bacteria, but a small new study suggests that microbes may live naturally in this part of the male reproductive system.

Human sperm cells are well-studied, so scientists were completely surprised to find a previously unknown structure in the little swimmers.

What's the story behind a mysterious gathering of octopus mothers?

A lack of new babies for endangered Northern Atlantic right whales makes their future even more uncertain.

Pesticide residue on fruits and vegetables may hurt women's fertility, a new study suggests.

Female killer whales reproduce between the ages of 12 and 40 years but can survive into their 90s.

More than two dozen viruses can make their way into human semen.

A woman in Arizona who was born without a vagina — the result of a rare condition — is speaking out about her condition.

In a surprising case, a drug that is normally toxic to ovaries actually helped one woman get pregnant.

Diatoms, long thought to reproduce asexually, do engage in sexual reproduction, with ammonium acting as an aphrodisiac.

Scientists are still trying to make sense of something extremely weird that happened between a pair of Ambystoma salamanders millions of years ago.