Figure 1. Physical constraints at the margin maintain epithelial tension in the wing.
(A) Cartoon depicting a pupal wing at 32 hAPF. Dashed double-sided arrows depict the proximal-distal (PD) and anterior-posterior (AP) axes. The PD axis is defined by a regression line passing through selected sensory organs (red dots) that are easily identifiable in Ecad::GFP expressing wings. The x axis is defined to correspond to the PD axis pointing distally, and the y axis is defined to correspond to the AP axis pointing anteriorly. L2–L5 indicate longitudinal veins 2–5. Brown dashed line outlines the cuticular sac surrounding the wing epithelium. Scale bar 20 µm. (B, B′) Show the distal end of a wild-type (WT) Ecad::GFP-expressing wing at 24 hAPF (greyscale in B, B′) and the same wing 3.5 min after laser ablation in the space between wing margin and cuticle (magenta in B′). The blue dashed line indicates the site of laser ablation. (B′′) Shows wing margin displacement measured with respect to the cuticle (brown dashed line in B′) along the white dotted line in (B′). Experimental points (magenta) were interpolated by a polynomial (blue line). (C–F) Show 32 hAPF wings that were unperturbed (C) or subjected to laser ablation at 22 hAPF (D–F). Ablation of the connections between the wing margin and the cuticle were performed in different regions, indicated by blue dashed lines in (D–F), and lead to altered wing shapes at 32 hAPF compared to the unperturbed control (C). Scale bar 100 µm.