Abstract The epidermis, the intestinal epithelium and the bone marrow are constantly renewed. Once a terminally differentiated cell has fulfilled its function, it is eliminated. Thus, new differentiated cells need to be constantly produced by the proliferative compartment to ensure the function of the tissue. As this process continues throughout a lifetime, cells must exist with a large capacity for proliferation within each of these tissues. These cells must also be the depository of all the information necessary for suitable differentiation to occur. This cell population which is qualified as the stem population, has attracted, in recent years, considerable attention not only because of its role during development, but also because of its potential sensitivity to radiations and carcinogenesis and to antineoplastic drugs. The epidermis, which is a stratified and squamous epithelium, has appendages which developed from the primitive epidermis during embryonic life. These appendages are also renewed during the adult lifetime, as illustrated by hair growth. The epidermis proves to be a unique model with which the development and the renewal of a stratified epithelium can be studied.