The zebrafish heart is similar to the human heart in many respects. But unlike the human heart, the fish heart closes wounds rapidly and then regenerates to nearly full function. Fibroblast growth factor (FGF) is an important molecule in the regeneration process.
Urodele amphibians—newts and salamanders—are able to regenerate fully functional limbs in response to amputation. Cells in and near the limb stump dedifferentiate to form a mass of stemlike cells that can produce all the specialized tissues of the limb, such as muscle, nerves, and blood vessels.