After the egg has been fertilized by a sperm, the surrounding egg coat tightens, mechanically preventing the entry of additional sperm and the ensuing death of the embryo, a new study finds. The work ...

Egg fertilization is often described as an epic swim meet: Millions of sperm swim as fast as they can toward the egg until one — the fastest, strongest, healthiest sperm of them all — wins the race ...

Katsuhiko Hayashi pulls a clear plastic dish from an incubator and slides it under a microscope. "You really want to see the actual cells, right?" Hayashi asks as he motions toward the microscope.

Using Google’s AlphaFold, researchers identified the bundle of three sperm proteins that seem to make sexual reproduction possible. By Elizabeth Preston They’re the original odd couple: One is massive ...

Human embryos have been developed from eggs given the DNA of adult skin cells – a feat that had previously been achieved in mice. This could one day provide a way for same-sex couples or women with ...

In a scientific breakthrough that raises a number of medical and ethical issues, researchers have used stem cells to create living, growing models of a human embryo. Because stem cells were used, ...