Zebrafish midline tissues coordinate their growth during embryonic development using a leader-follower strategy described by formation control, as reported by researchers from Japan and the U.S. The notochord leads elongation, while adjacent tissues grow and migrate with it in response to fibroblast growth factor gradients, cadherin-2-mediated cell adhesion, and mechanosensory Yap signaling. The researchers could replicate this behavior using a mathematical model, revealing a control theory-based principle for harmonized tissue development in embryos.