Charting the unknown currents of cellular flows and forces.

One of the central questions in developmental biology concerns how cells become organized into tissues of the correct size, shape and polarity. This organization depends on the implementation of a cell's genetic information to give rise to specific and coordinated cell behaviors, including cell division and cell shape change. The execution of these cell behaviors requires the active generation of mechanical forces. However, understanding how force generation is controlled and, importantly, coordinated among many cells in a tissue was little explored until the early 2000s. Suzanne Eaton was one of the pioneers in this emerging field of developmental tissue mechanics. As we briefly review here, she connected the quantitative analysis of cell behaviors with genetic assays, and integrated physical modeling with measurements of mechanical forces to reveal fundamental insights into epithelial morphogenesis at cell- and tissue-level scales.