Epithelial stem cells in gastrointestinal morphogenesis, adaptation and carcinogenesis.

Epithelial stem cells have a central role in the physiological maintenance of epithelial tissues in a steady state. In addition it is becoming clear that these cells may also be implicated in the generation of metaplastic epithelia and ultimately the generation of neoplastic epithelia. This review aims to compare and contrast stem cells and their functions in different areas of the gastrointestinal tract in an attempt to emphasise unifying concepts. New methods of 'organotypic' cell culture can potentially be applied to the study of gastrointestinal stem cells and are, therefore, also discussed.