Tissue mechanics in morphogenesis: Active control of tissue material properties to shape living organisms

Cellular forces translate into epithelial deformations to shape animal organisms. To set the proper deformations, these forces are modulated in space and time during development. However, several studies have recently highlighted that, in addition to forces, tissue mechanical properties are also actively controlled in space and time to determine the final tissue shape. In this review, we present the different ways used by epithelial tissues to regulate their mechanics and deformability. The choice of one or combination of modes to control mechanical properties is context dependent. Thus, we will first present our current knowledge on tissue mechanical properties, the cellular strategies to modulate them, and the methods used to assess them. We will then present a few examples in which control of epithelial mechanical properties impacts morphogenesis.