Shaping the body plan is a complex process that involves the spatial organization and patterning of the different germ layers. Using gastruloids –3D aggregates of mouse embryonic stem cells- we study at cellular resolution the specification of the endoderm. First, we show that contrary to mesoderm, nascent endoderm does not undergo epithelial-mesenchymal transition. Second, we provide evidence for a role of tissue flow, and heterogeneity of cellular junction tension, in the sorting and differentiation of the islets of endoderm cells.
And yet it diffuses!
Free diffusion of Wnt ligands can polarize target cells at distance in C. elegans embryos.
