Figure 5

A finite element model based on oldest cell divisions with noise can recapitulate most features of the mitotic shift. (A) Initial conditions and model output. Cells are chosen for division as a function of cellular age, with additive noise in the division ordering. The simulated tissue has toroidal boundary conditions, and undergoes at least 1050 mitoses. (B) The simulated distribution of cellular shapes. (C) The distribution of mitotic cells chosen for division. (D) Division likelihood as a function of polygon class, here displayed relative to the likelihood that a nonagon divides (which is taken to be 1). Panel (D), which is computed using Bayes rule, is well fit by an exponential function (the R² coefficient is equal to 0.9989). (E) The simulated mitotic shift based on an oldest-cell division mechanism. (F) For comparison, the mitotic shift in Drosophila and in Cucumis. Sample sizes for the empirical overall and mitotic distributions are given under the heading “Sample sizes for overall and mitotic cell shape distributions” in the Methods section.