An attractive model for studying stem cell differentiation within a live animal is the planarian flatworm. Regeneration is studied by simple amputation experiments that are easily performed in a basic laboratory and are amenable to pharmacological and genetic (in vivo RNAi) manipulation as detailed by protocols in this article.
Chan, J. D., Marchant, J. S. Pharmacological and Functional Genetic Assays to Manipulate Regeneration of the Planarian Dugesia japonica. J. Vis. Exp. (54), e3058, doi:10.3791/3058 (2011).