Two-dimensional froths and the dynamics of biological tissues

Two-dimensional foams are used to model the evolution and the steady state of biological tissues. When only cell division occurs, we deduce the mode of division simply from the stationary distribution of the number of sides per cells, by inverting a system of coupled rate equations. Comparisons with experimental data confirm the method. We then discuss the time evolution of tissues evolving both through cell division and cell disappearance, theoretically and by topological simulations. Simulations reproduce realistically the steady state of the innermost layer of the human epidermis. We conclude that short-ranged topological information is sufficient to explain the evolution and stability of biological tissues. @S1063-651X~98!08111-2#