blastema
A blastema is a mass of cells capable of growth and regeneration into organs or body parts. Historically blastema have been thought to be composed of undifferentiated pluripotent cells, but recent research indicates that in some organisms blastema may retain memory of tissue origin.[1] Blastemata are typically found in the early stages of an organism's development such as in embryos, and in the regeneration of tissues, organs and bone[WP]. A regenerating tissue composed of a proliferative mass of undifferentiated progenitor cells from which new differentiated structures arise[ZFA].