Practice question

Stem cell-mediated regeneration relies on persistent adult stem cells that continuously supply differentiated derivatives. In planarians, population of clonogenic neoblasts, pluripotent adult stem cells expressing piwi-1 and prog-1, migrates toward wounds, proliferates massively, and differentiates into everything including epidermis, gut, muscle, and central nervous system. Single cNeoblast can rescue lethally irradiated animals. Zebrafish fin regeneration uses dedifferentiation-based blastema classified as epimorphosis, Hydra budding combines stem cell activity with morphallactic remodeling, mammalian liver regeneration uses compensatory proliferation of differentiated hepatocytes rather than dedicated pluripotent pool, making planarian example textbook stem cell-mediated.