Lineage selection and plasticity in the intestinal crypt

We know more about the repertoire of cellular behaviours that define the stem and progenitor cells maintaining the intestinal epithelium than any other renewing tissue. Highly dynamic and stochastic processes define cell renewal. Historically the commitment step in differentiation is viewed as a ratchet, irreversibly promoting a given fate and corresponding to a programme imposed at the point of cell division. However, the emerging view of intestinal self-renewal is one of plasticity in which a stem cell state is easily reacquired. The pathway mediators of lineage selection are largely known but how they interface within highly dynamic populations to promote different lineages and yet permit plasticity is not. Advances in understanding gene regulation in the nervous system suggest possible mechanisms.