Contact inhibition can drive cell dispersal and tissue ordering

During gastrulation, the endodermal cells of the developing zebrafish embryo undergo a period of dispersal mediated by contact inhibited locomotion (CIL) followed by a period of convergence into the arrangement that forms the epithelial tissue sheet. In vivo observations have found the final distribution of endodermal cells to be highly regular and free of defects or density fluctuations. We propose a particle based model that couples force and torque to simulate CIL behavior. This model exhibits a continuum of behaviors resembling the cell motions of various germ layers across a wide range of densities. This model can produce hyper uniform dense packings, highly disordered phases, and flowing regimes. Our results show how cell-to-cell interactions, despite lacking explicit alignment terms, are capable of forming organized packings and flowing behaviors as well as the consequences of surface curvature on these phenomena. This spectrum of behaviors produced by the model is compared with in vivo wild-type endodermal cells as well as genetic and pharmacological perturbations that limit CIL.