Activity driven buckling in early steps of organogenesis

Morphogenesis, the complex process by which the shape of organs and organisms emerges from cell organization, intertwines chemical and physical processes. In many situations, 3D biological structures are achieved through targeted active folding processes of 2D tissue layers. An example is the process of lumen formation – the buckling, folding and invagination of a planar cell sheet that leads to the formation of a hollow cavity enwrapped by a polarized epithelium. In this talk, starting with an active elastic continuum description of a cellular tissue layer of finite thickness, we derive an effective 2D model that includes contractility and cell division. We show that the model can account for the buckling instability at the onset of lumen formation. We find that traction localizes contractile stresses at the boundary of the tissue, while cell division induces an in-plane outward pressure. These two competing effects destabilize the initial planar state forcing the tissue to buckle.