Human sperm have long been a subject of fascination—not just for their role in fertilization, but for their remarkable ability to navigate through some of the most viscous environments in the body.

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 ...

Research into how a father’s choices — such as diet, exercise, stress, nicotine use — may transfer traits to his children has become impossible to ignore. The standard sperm-meets-egg story posits ...