Reproductive System

Women undergoing a particular chemotherapy had a much greater number of eggs in their ovaries than expected, a finding that surprised researchers.

Having your last baby in your late 30s may be good for your brain.

Skin cells from mouse moms were matured in a lab dish and developed into baby mice. The feat is a step toward a similar process that one day may work in humans.

In two widow spider species, males deploy an ingenious strategy to avoid being cannibalized during sex.

Biologist and writer Carin Bondar leads the way into the intriguing world of animal sexual practices in her new book, "Wild Sex."

Combat between two different viper species has never been observed — until now.

The experiment resulted in the birth of healthy baby mice with a success rate of up to 24 percent.

A city in Japan says it will pay for egg freezing as a way to improve the country's low birth rate. But the procedure is not a perfect solution.

Some teensy fruit flies produce sperm more than 2 inches (5 centimeters) long.

A new study suggests another reason to avoid fast food.