How mechanical canalization shapes the gut tube

In the development of inner organs such as the gut, laminar sheets of cells wrap into tubes, fold into chambers, and coil into 3D chiral loops. The specific sequence of dynamic shape changes are essential for organ function. While the genes that regulate these processes are increasingly well catalogued, the mechanical programs that channel molecular activity into stereotyped geometries remain poorly understood. The embryonic Drosophila midgut provides a genetically tractable and optically accessible system to interrogate the mechanical principles that sculpt complex 3D organ tubes. Two planar sheets -- each composed of endoderm (epithelial) and mesodermal (muscle) layers -- wrap into a tube, which subsequently folds into chambers, then breaks left-right symmetry to form a chiral coil. I will present our work decoding the cellular mechanisms of these three steps -- tubulogenesis, folding, and coiling -- highlighting the mechanisms for robustness that canalize gut development into discrete developmental pathways, as well as the control knobs that switch the developmental program into alternative developmental trajectories. In each case, we find muscle cells are central drivers of tissue mechanics, programming tissue shape changes and driving transitions in the behavior of the underlying endoderm.