A blastema is a mass of undifferentiated cells capable of growth and regeneration intoorgans or body parts. Blastemata are typically found in the early stages of an organism'sdevelopment such as in embryos, and in the regeneration of tissues, organs and bone.

Some amphibians and certain species of fish can produce blastema as adults. For example, salamanders can regenerate many organs after their amputation, including their limbs, tail, retina and intestine. Most animals cannot produce blastemas; however, blastema research (as an alternative to stem cell research) was the subject of a 2006 New York Times article, which is cited in the External Links section.

When the limb of the salamander is cut off, a layer of epidermis covers the surface of the amputation site. In the first few days after the injury, this wounded epidermis transforms into a layer of signaling cells called the Apical Epithelial Cap (AEC), which has a vital role in regeneration. In the meantime, fibroblasts from the connective tissue migrate across the amputation surface to meet at the center of the wound. These fibroblasts multiply to form a blastema, which are the progenitors for the new limb.