Single-front and multiple-front 4-dpf cells are drawn from the same population, which is distinct from 2 dpf. (a–c) Cells from the indicated developmental stage and morphology were tracked for 20 min. 25 randomly chosen tracks are shown. (d and e) Histogram of velocity autocorrelation decay constants for 2-dpf (n = 138) and 4-dpf (n = 177) tracks. Smaller values indicate straighter tracks. (f) Phalloidin intensity, averaged over the entire cell, was measured in 2-dpf (n = 88) and 4-dpf single-front (n = 30) and 4-dpf multiple-front cells (n = 90). (g) Mean phalloidin intensity at the protruding edge was measured in 2-dpf (n = 88) and 4-dpf single-front (n = 30) and 4-dpf multiple-front cells (n = 90). **, P < 0.01; *, P < 0.05; n.s., P > 0.05, as measured by two-sample Wilcoxon rank sum test.