Fig. 5. R8 cells are sensitive to Dl in the spl mutant. (A,B) Boss labeling of R8 cells in spl mutant eye discs. (C,D) SEMs of adult eyes from spl mutants. (B,D) R8 cell number, adult eye size and number of ommatidia are significantly reduced by elevated Dl expression targeted posterior to the morphogenetic furrow by GMR Gal4. Compare with the insensitivity of R8 cells to targeted Dl expression in the absence of the spl mutation (Fig. 2).