Signaling and Mechanics influence the number and size of epithelial rosettes in the migrating zebrafish Posterior Lateral Line primordium.

A prepattern of Fgf signaling triggers formation of epithelial rosettes as protoneuromasts form periodically in the migrating Posterior Lateral Line primordium. However, the number and size of epithelial rosettes is influenced by the balance of mechanical interactions that promote or oppose their formation. Selective slowing of leading cells in the primordium can result in the fusion of two rosettes to form one larger one, while slowing of trailing cells can result in splitting of a previously formed rosette to form two smaller ones. These observations can be accounted for by mechanics-based models, where local interactions associated with apical constriction and cell adhesion promote formation of rosettes, while tension along the length of the primordium, influenced by the relative efficacy of leading and trailing cell migration, opposes their formation. We describe computational models that illustrate how the relative speed of leading versus trailing cells, as well as changes in cell adhesion and mechanical coupling, can influence the pattern of protoneuromast formation and deposition by the migrating primordium. Our studies illustrate how signaling and mechanics together influence morphogenesis in the migrating primordium.