Organisms with complex morphological shapes arise from single cells through a process called morphogenesis. However, owing to the complexity of morphogenetic processes, it can be challenging to identify the cellular requirements that robustly produce developmental patterns. In their study, Isaac Salazar-Ciudad and co-workers model morphogenesis using EmbryoMaker, which simulates changes in the three-dimensional position of cells, to identify the minimal requirements allowing the formation of robust complex shapes. Their analysis of various genetic networks reveals that only a few of them produce complex morphologies; however, these morphologies are typically very variable. They show that the formation of complex shapes demands only that, over time, a large fraction of cells in the embryo alter their mechanical properties and cell behaviours, in particular cell contraction and cell division. Morphological robustness is achieved through extracellular signalling, which acts to compartmentalise and synchronise cellular behaviour within a group of cells. However, the authors find that robustness only results from the coordination of the contractile behaviour of cells, but not cell division events. Together, these findings suggest that robust morphological development of embryos requires their compartmentalisation into regions of coordinated cellular behaviour, which is achieved through extracellular signalling.
