Differential cell adhesion has long been postulated to play important roles in cell sorting and cell migration; however, these roles have been studied in very few specific contexts. Thus, the deployment and utility of differential adhesion as a developmental mechanism remains somewhat unclear. Cortes et al. find that a dynamic wave of characteristic cadherin expression moves through the
developing somite, and is required to guide adaxial (presumptive slow twitch) muscle cells across the entire width of the myotome. This work establishes important principles underlying the contribution of differential cell adhesion to vertebrate morphogenesis.