Author response image 1. Changing the polarized direction of a plane of cells does not rotate the plane as a whole but breaks it into smaller planes.

Time t = 0 shows a plane consisting of 500 cells with AB polarity pointing to the right. At time t = 0.1, the direction of the polarity is shifted by 45 degrees. Since the polarity is fixed in time, the planes break into smaller pieces, and at time 10⁴ they have merged into two planes that are separated by several cell diameters.