Fig. 3. Expression of the chimeric di integrin in the wing imaginal disc induces cell shape changes, detachment of the basal lamina and disorganisation of the basal matrix. Wild-type wing discs (A-C) or wing discs expressing the di chimera in the posterior region of the wing disc (p) driven by the engrailed–GAL4 line (enG4: F,G,H,E,J). (D,I) di expressing clones in the wing pouch. (A,F) Filamentous actin staining with Rhodamine-phalloidin in early third-instar larval discs shows that expression of the di chimera leads to the formation of extra folds – compare the posterior side (p) with the anterior wild type (a). This was better visualised by scanning electron microscopy (B,G). (C,H) In cross-sections of wing discs, the expression of di clearly leads to a reduction in cell height (arrows in C and H point to the width of the epithelium). (D,I) Cells expressing di (green in D) also expand their apical cell surface as seen with an anti-phosphotyrosine antibody (red). (E) Localisation of laminin A to the basal side of wild-type cells is also affected by di expression, compare posterior experimental side (p) with that of anterior wild type (a) in either an xy (E) or an xz confocal (E') section. (J) Similarly, di expression affects the organisation of a second form of basal matrix. Bars, 8 µm (D,I) and in 30 µm (E,J).