Modelling the 3D dynamics of a biological tissue in vivo

The epithelial shape changes driving morphogenesis result from internal mechanical forces arising from the cellular cytoskeleton. The actomyosin network is a cellular cytoskeletal component capable to exert contraction stresses. Cellular actomyosin stresses can eventually be integrated at the scale of a tissue or of the entire organism through cell–cell adhesions. During early Drosophila embryo development, the actomyosin network is known to play a key role in the folding of the prospective mesoderm by forming a furrow on the ventral side of the embryo. Here, we show that actomyosin contractility at the embryo surface works like a ‘cheese-wire’ indenting the surface in a rectilinear fold after a buckling event.