Live and let die in the intestinal epithelium

The intestinal epithelium is a relatively simple developmental system and a prime example of tissue renewal from a source of multipotent stem cells. Throughout adulthood, intestinal epithelial proliferation, cell-fate specification and differentiation are coupled to migration in discrete units known as crypts of Lieberkuhn. Physically guided by Eph receptors and their ligands, the ephrins, stem cell progeny transit through the proliferation/differentiation switch, and Notch diversifies their subsequent fates. Writ signalling appears to control most of these events.