Fig. 3. dRheb overexpression causes eye and head overgrowth. Combination of GMR-GAL4 (which drives expression in the eye imaginal disc) with dRheb^AV4 results in marked overgrowth of the eye (E,F) compared with the wild type (A,B) or driver alone (C,D). Eye and head overgrowth is even more dramatic (G-J) when ey-FLP-induced GAL4-expressing clones overexpress dRheb in dRheb^AV4/+ eye and antennal discs. (A,C,E,G,I) Lateral views of eye. (B,D,F,H,J) Frontal views of head. Scanning electron microscopy shows that, compared with the wild-type (K), dRheb-overexpressing eyes have enlarged ommatidia and bristles, as well as irregular and occasionally fused ommatidia and extra bristles (L). Solid arrows, bristles; dashed arrows, extra bristles; black arrowhead, fused ommatidia.