A mesoscopic description of contractile cytoskeletal meshworks.

Epithelial morphogenesis plays a major role in embryonic development. During this process cells within epithelial sheets undergo complex spatial reorganization to form organs with specific shapes and functions. The dynamics of epithelial cell reorganization is driven by forces generated through the cytoskeleton, an active network of polar filaments and motor proteins. Over the relevant time scales, individual cytoskeletal filaments typically undergo turnover, where existing filaments depolymerize into monomers and new filaments are nucleated. Here we extend a previously developed physical description of the force generation by the cytoskeleton to account for the effects of filament turnover. We find that filament turnover can significantly stabilize contractile structures against rupture and discuss several possible routes to instability resulting in the rupture of the cytoskeletal meshwork. Additionally, we show that our minimal description can account for a range of phenomena that were recently observed in fruit fly epithelial morphogenesis.