In a common metaphor used to describe human fertilization, sperm cells are competitors racing to penetrate a passive egg. But as critics have noted, the description is also a 'fairy tale,' rooted in ...

At this stage, known as gastrulation, a flat and featureless sheet of cells folds into a living blueprint for the body, a fleeting ...

The international body representing stem-cell scientists has torn up a decades-old limit on the length of time that scientists should grow human embryos in the lab, giving more leeway to researchers ...