Researchers at Newcastle University in England report they have coaxed the first human sperm cells from embryonic stem cells, in a remarkable demonstration of how quickly the field of stem-cell ...

We all know the drill for reproduction—sperm meets egg. But mice aren’t people. And the same recipe doesn’t work for human reproductive cells. One reason, according to Dr. Mitinori Saitou at Kyoto ...

Male fertility rates have been plummeting over the past half-century. An analysis from 1992 noted a steady decrease in sperm counts and quality since the 1940s. A more recent study found that male ...