Curado, S., and Stainier, D.Y. (2006) The HeArt of Regeneration. Cell. 127(3):462-464.
Fish and amphibian hearts are known to regenerate after partial resection, but the molecular mechanisms underlying this process remain unclear. In this issue of Cell, analyze regeneration in the zebrafish heart. Their work indicates that new cardiomyocytes originate from undifferentiated progenitor cells and reveals a critical role for the epicardium, the cellular layer that covers the heart.