As cells migrate — during processes such as development and wound healing — they transmit forces from their leading edge, creating a stress wave that propagates through the mass of expanding tissue.

Xavier Trepat at the Institute for Bioengineering of Catalonia in Barcelona, Spain, and his colleagues measured the inter- and intracellular mechanical forces in a monolayer of canine epithelial cells as the cells spread out on a substrate. As the leading front commenced migration, forces were generated that were transmitted backward from cell to cell through intercellular junctions as the cells moved forward. A slow mechanical wave propagated through the cells, building up gradients of stress that helped to direct the migration.

Nature Phys. http://dx.doi.org/10.1038/nphys2355 (2012)