Authors: A. Erzberger, A. Jacobo, A. Dasgupta1 and A. J. Hudspeth
Actively regulated symmetry breaking, which is ubiquitous in biological cells, underlies phenomena such as directed cellular movement and morphological polarization. Here, we investigate how an organ-level polarity pattern emerges through symmetry breaking at the cellular level during the formation of a mechanosensory organ. Combining theory, genetic perturbations and in vivo imaging, we study the development and regeneration of the fluid-motion sensors in the zebrafish’s lateral line. We find that two interacting symmetry-breaking events—one mediated by biochemical signalling and the other by cellular mechanics—give rise to precise rotations of cell pairs, which produce a mirror-symmetric polarity pattern in the receptor organ.