Fig. 5. Evolutionary transitions in gastrulation patterns.

A critical morphogenetic parameter p₀ models the amount of EMT or active cell ingression caused by the cell’s propensity to ingress given apical myosin-induced isotropic contraction. The initial condition m(x, t₀) models the extent of the mesendoderm precursor territory. Changing cell behaviors p₀ and initial cell types m(x, t₀) (left column), our model recapitulates the flow patterns in the phylogeny of vertebrate gastrulation from a self-organizing dynamical structure. Our model-based predicted flow patterns mimic those naturally observed in reptiles, amphibians, and fish, and are reproduced experimentally, in vivo, in the chick embryo [see also the recently published paper (4) for details on the experiments]. The right columns show deformed Lagrangian grids overlaying the light-sheet microscope images from perturbed chick-experiment velocities (4) and deformed Lagrangian grids from the predicted model velocity for each gastrulation mode. Scale bars, 500 μm.