Planarian flatworms are animals with the amazing ability to regenerate from an infinite variety of injuries. For example, if a worm is cut into ten different pieces, each of those pieces will regenerate a complete animal! Planarians use pluripotent stem cells (top) to regenerate all of their organ systems, including eyes (upper left), muscle (upper right), intestine (bottom left), and central nervous system (bottom right).

We seek to understand how a population of pluripotent stem cells can give rise to a diversity of differentiated tissue types during regeneration and homeostasis. The tissue types shown in this image illustrate the versatility of these stem cells, the complexity of our challenge, and the beauty of this biological system.