A mechanochemical model recapitulates distinct vertebrate gastrulation modes

During vertebrate gastrulation, an embryo transforms from a layer of epithelial cells into a multilayered gastrula. This process requires the coordinated movements of hundreds to tens of thousands of cells, depending on the organism. In the chick, patterns of myosin cables spanning several cells drive coordinated tissue flows. How this coordinated activity emerges and spatially evolves into large-scale patterns in a developing organism remains unresolved. We derive a minimal theoretical framework that couples actomyosin activity to tissue flows, thus providing the basis for gastrulation dynamics. Our model predicts the onset and development of gastrulation flows in normal and experimentally perturbed chick embryos as a spontaneous instability. Varying the initial conditions and a critical parameter associated with active cell ingression, our model recapitulates the phase space of gastrulation morphologies seen across vertebrates, consistent with experiments. Altogether, our results suggest that relatively small changes in the organization of critical cell behaviors associated with different force-generating mechanisms contribute to distinct vertebrate gastrulation modes via an evolvable self-organizing mechanochemical process.