Stem cells’ powers of self-renewal, immortality and potential for medicine inspire those who study them. But progress toward understanding them has been slow — it took 20 years just to figure out how to grow embryonic stem cells in the laboratory. More recently, though, molecular techniques have enabled swift movement on two fronts. Researchers are starting to see how stem cells can replenish their numbers while giving rise to specialized cells. Others are learning how to turn adult skin cells into cells more like their embryonic ancestors. These advances offer hope that sci...

Mice may use a cluster of neurons known as the Grueneberg ganglion to detect alarm pheromones.