Fig. 1. PD gradient in the levels of DE-Cad and cell shapes in wing imaginal disc epithelium. (A) Wing imaginal disc displaying Wg (blue) and Q-vg-lacZ (green). (B,C) Cartoons of optical section along the XY (B) or the XZ (C) plane reveal, respectively, cell shape and relative position of AJs (green in C) along the AP axis of the columnar pseudo-stratified epithelium. Nuclei are shown in magenta (C). (D-D'') In cells flanking the DV boundary (arrow), levels of both DE-Cad (D and red in D'') and Arm-GFP (D' and green in D'') are upregulated (merge, D''). (E) A high-resolution image of the AJs marked by DE-Cad-GFP (grey) in the XY optical plane reveals PD gradation in both DE-Cad levels and apical cell shapes; cells of the DV boundary are marked by Wg (blue). (F-F'') XZ section across the DV boundary of a wing disc epithelium reveals upregulated DE-Cad (F) and F-actin (rhodamine-phalloidin, F') in the AJs of cells, which flank the DV boundary (arrow). In the merge (F''), the DV boundary is marked by BE-vg-lacZ (blue); nuclei are marked by DAPI (magenta).