Directed cohort migration results in the formation of the rod-shaped notochord. a Visual rendering of the results of the simulations. See Supplementary Fig. S6 for the description of the cellular Potts model. b Embryos were microinjected with mRNAs for the indicated constructs (pcdh18a: 0.3 ng, e-cad: 0.4 ng, dyn2K44A: 0.2 ng). At 5 hpf, approximately 50 cells were grafted into the lateral embryonic margin of uninjected host embryos (n = 5). At 8 hpf, the migration and the directionality of the cell clusters were analysed. Animal pole was set to 0°, vegetal pole was set to 180°. Blue line indicates mean value of clonal coverage measured in ten different embryos per experiment and white lines indicate SEM. c Embryos from b were fixed and subjected to ISH for the lpm marker myf5. Horizontal cross sections revealed the formation of an ectopic rod-shaped structure of the Pcdh18a-positive clones in the lpm (yellow arrow). d Schematic summary of the function of the ppl in notochord morphogenesis. Pcdh18a/E-cadherin adhesion complexes (orange dots) increase cell adhesion within the ppl, leading to the cluster formation (left). In parallel, Pcdh18a controls endocytosis of E-cadherin adhesion complexes to allow fast cohort migration of the ppl cluster (right) to orchestrate intercalation of notochord cells. Scale bar: 100 µm
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