Cell proliferation studies in the intestinal epithelium of the rat: II. Theoretical aspects

A model of the intestinal crypt, based on the results of the preceding paper, is presented. The model describes a steady state in which at the bottom of the crypt divisions give rise to cells which will in turn divide, and near the top of the crypt to cells which will differentiate without dividing. By means of theoretical phase distribution diagrams, the labelling and mitotic indices at various levels in the crypt are predicted and compared with those found by experiment; in this way the model is substantiated. The biological implications of the model are considered.