Alignment of cytoskeletal structures across cell boundaries generates tissue cohesion during organ formation

One of the most fascinating aspects of development is the complexity and diversity of tissues and organs that are formed from simple primordia, involving complex coordination between large groups of cells. Lack of coordination leads to developmental defects and failure in organ formation. The simple primordia are often polarised epithelial sheets, with cells connected to neighbours apically via Cadherin-based cell-cell junctions that intracellularly link to the cytoskeleton. Coordination of cells in epithelia during morphogenesis occurs in part at these junctions. Furthermore, in many tissues a striking supracellular order and alignment of cytoskeletal structures can be observed, likely playing an important part in the coordination of cells. Here, we will introduce examples of morphogenetic events where this supracellular order of the cytoskeleton is very apparent and will discuss recent advances in understanding the generation and function of this order.