Quality control. TStem cells (color enhanced) somehow keep their chromosomes in good shape. Credit: Andrew Paul Leonard/Photo Researchers Inc. A long-standing belief in stem cell biology is that stem cells circumvent classic cell division to keep their daughter cells healthy. But new results show that this isnt true after all; stem cells divide just like any other cell, parsing their chromosomes randomly between the progeny. To keep organisms running smoothly, stem cells rejuvenate tissues by providing a constant supply of fresh cells. But every time a stem cell copies its chromosomes, it puts itself at risk of generating mutations in...