Patterns of C&E movements in the axial and presomitic mesoderm. (A and D) Lateral views of live embryos at the one-somite stage (10.5 hpf). The regions where the time-lapse recordings were taken are indicated by brackets. (B and E) Snapshots of PIV analyses of C&E movements at the one-somite stage, showing the tissue displacements within a 9-min time window. Dorsal views, anterior to the top. Arrows indicate the direction of cell movements, whereas the length of the arrows represents the movement speed. (C and F) Same images as shown in B and E, except that different movement speeds are presented in a color-coded manner. Purple lines delineate the axial mesoderm. (G–J) Snapshots of the analyzed medial PSM cell population at the beginning and the end of the time-lapse recordings. Dorsal views, anterior to the top. Red arrows illustrate the maximum length and width of the analyzed cell population when the time lapse started. (K) Quantification of the tissue shape changes (Materials and methods). 10 embryos of each genotype were analyzed. Error bars represent the standard error. *, P < 0.05; **, P < 0.005, mutant vs. WT. A, anterior; P, posterior; Axial, axial mesoderm. Bars: (A and D) 100 μm; (B, C, E, F, and G–J) 20 μm.