Stochastic models for the evolution of stem cells in colon crypts

The human colon contains about 15 million crypts, each of which contains about 2,000 cells. Some of these are stem cells that maintain their population size when they divide, and some are transit amplifying (TA) cells that divide and differentiate to become the cells that repopulate the colon. It is of some interest to understand the behavior of stem cells in a typical crypt