Eggs and more grown from mouse stem cells

In a series of recent experiments, scientists have transformed cells from mouse embryos into skin, heart muscle, and even eggs. In addition to providing insight into how such tissues develop, these feats have renewed the political and ethical debate over whether similar experiments should be conducted with cells derived from human embryos.

Known as embryonic stem cells, the lab-grown mouse cells are unspecialized and can grow in lab dishes seemingly forever.