Epithelia consist of tightly packed cells in which the apical cell surfaces resemble polygons with different numbers of neighbouring cells. But how is this topology, which ensures the structural integrity of epithelia, established during development? On p. , Tinri Aegerter-Wilmsen and colleagues propose that growth regulation by mechanical stress might help to establish epithelial topology. Previously, it has been proposed that cell division alone, or cell division plus cell rearrangements, is sufficient to explain epithelial topology. Now, the researchers formulate two variant models in which cellular growth rates are dependent on mechanical force. A comparison of the predictions of these models with experimental data on the clustering and the polygon distribution of mitotic cells in the Drosophila wing imaginal disc shows that only the models that include mechanical feedback fit the experimental data. These models also show a reduction in cell rearrangements and eliminations during epithelial growth. Thus, growth regulation by mechanical stresses could help to ensure the structural integrity of growing epithelial tissues.
