Fig. 3. Loss of gp150 function causes defective eye development. SEM images (A, C and E) and tangential sections (B, D and F) of adult eyes are presented. (A and B) Wild type. The inset highlights seven R cells arranged in a trapezoidal configuration in each ommatidium and the rhabdomere of R8 cannot be seen in this apical section. (C and D) gp150² mutants. About 35% (n = 522) of the ommatidia contain either too many or too few R cells. The arrow indicates a fused ommatidium. At basal levels, ommatidia with multiple R8-like cells were observed (data not shown). Other gp150 alleles exhibit similar phenotypes. (E and F) In gp150² GMR-gp150 flies, overexpression of gp150 in the eye effectively rescues the mutant eye phenotype, with >93% (n = 368) of the ommatidia containing a normal complement of R cells. The arrow indicates a mutant ommatidium occasionally seen in this genotype. Anterior is to the left, except (D), in which anterior might be to the top.