Platyhelminthes (flatworms) have captivated the imagination of biologists for centuries. Indeed, planarian flatworms were used as experimental models decades before Caenorhabditis elegans became known as 'the worm'. Although planarians experienced a brief fall from grace, with the advent of molecular tools, planarians, such as Schmidtea mediterranea, have emerged in recent years as powerful mod...

Why does regeneration take place in some animals but not others? Increased understanding of gene function is required to dissect the genetics, cell biology, and physiological aspects that make regeneration possible. An unlikely model animal, the planarian Schmidtea mediterranea, is proving valuable in this endeavor.

The planarian Schmidtea mediterranea is rapidly emerging as a model organism for the study of regeneration, tissue homeostasis and stem cell biology. The recent sequencing, assembly and annotation of its genome are expected to further buoy the biomedical importance of this organism. In order to make the extensive data associated with the genome sequence accessible to the biomedical and planaria...

www.sciencemag.org SCIENCE VOL 332 13 MAY 2011 757 COVER Composite confocal image of an adult planarian (Schmidtea mediterranea) showing a growing colony of dividing cells (red) that initiated from a single, pluripotent stem cell called a clonogenic neoblast (cNeoblast). The ~1-millimeter-long animal is visualized with differential interference contrast microscopy and nuclear staining (blue). T...