Epithelial tension is highest along the length of the furrow. (A) Myosin-GFP images immediately after laser incisions (red lines, 20 µm) were made perpendicular to (top) or parallel to (bottom) the furrow. Myosin displacements perpendicular to these incisions (D_ap and D_vl) were measured. Bar, 20 µm. (B) D_ap and D_vl as a function of distance from the laser incision. The data were grouped into 4-µm bins (0–4, 4–8, etc…) and data points are mean ± SEM (indicated by error bars; n = 4 embryos). (C) D_ap as a function of distance for H₂O-injected (control) and twiRNAi embryos. Data points are the same as in B (n = 5 embryos). (D) Myosin-GFP images before (top) and after (bottom) a point ablation (crosshair). In the bottom panel, the post-ablation image (red) overlays the pre-ablation image (blue) to illustrate myosin displacement. Bar, 20 µm. (E) Schematic illustrating the method used for quantifying radial myosin displacement (D_r) in the direction (θ) relative to the a-p and v-l axes. Radial displacement is the component of the measured displacement (D) along direction θ. (F) D_r as a function of θ. The data were grouped into bins of 30° and data points are mean ± SEM (indicated by error bars; n = 5 embryos).