This animation shows how zebrafish can rapidly heal wounds to the heart.

When the human heart is severely wounded — during, for example, a heart attack — it cannot regenerate the damaged muscle tissue. However, a damaged zebrafish heart can recover most of its original shape, size, and function over time. The animation illustrates the steps in this regeneration process, highlighting the role of cell signaling proteins called fibroblast growth factors (FGF).

This animation is a clip from a 2006 Holiday Lecture Series, Potent Biology: Stem Cells, Cloning, and Regeneration. Depending on students’ background, it may be helpful to pause the animation at various points to discuss different features of the heart or steps in the regeneration process.