In the United States, an estimated 645,000 men ages 20 to 50 have azoospermia, a condition in which no sperm are present in their ejaculate. Now, scientists are testing a potential treatment: ...

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.

Imagine a future where a diagnosis of untreatable male infertility is no longer the end of the road—because science has found a way to produce human sperm from lab-engineered testicular tissue. This ...

Jaiwen Hsu was an active 11-year-old when he developed pain in his left knee that forced him to sit out a few soccer games. What his parents thought was a sports injury turned out to be osteosarcoma, ...

A man in his early 20s received a transplant of his own sperm-producing stem cells, which had been frozen since his childhood, in an attempt to regain fertility. Doctors are waiting to see if the ...