POSSIBLE MODELS DESCRIBING ENTEROCYTE REPLACEMENT IN MOUSE PEYERS PATCH FOLLICLE-ASSOCIATED EPITHELIAL TISSUE

Epithelial cells emerging from intestinal crypts surrounding Peyer's p atch lymphoid follicles can be shown in chimaeric mice to adopt a wedg e-like formation during migration to a central zone of cell extrusion (Schmidt et al. 1985). Similar tissue taken from normal mice has been used as a model in the present work to investigate how such a pattern of convergent migration might take place. Tissue treated cytochemicall y to reveal differences in surface alkaline phosphatase activity enabl ed a number of cell surface area measurements to be carried out by ima ge analysis. The position where these measurements had been taken was then related to the geometrical centre of the tissue. Epithelial cell surface area halved during migration from edge to centre of these disc -like structures. An equation used to describe the positional dependen ce of this change had the form rho(r)=6.86r-0.24, where rho is cell de nsity and r is cell distance from the centre measured in micrometres. Further calculation showed this decrese to be insufficient to explain all features associated with convergent migration. Differential change s occurring in the rate of cell migration and premature cell loss were also considered as possible factors affecting migration patterns. Mat hematical modelling of these variables produced a migration pattern co nsistent with previous experimental findings. This model assumes that half the cell population is lost during migration and that cell migrat ion rate near the centre is four times greater than at the edge. It sh ould be possible to test this latter prediction in future experiments.