Fig. 7. Loss of Apc2 increases the width of the dorsal rim area. Second and third row ommatidia expressing Hth (green) are marked with yellow arrowheads. Photoreceptors are marked with anti-Elav (blue). The number of second and third row ommatidia expressing hth increases when Apc2 activity is severely reduced. (A) Wild-type, (B) Apc2³³/Apc2³³ and (C) Apc2³³/Df(3R)w6. (D) The number of second row ommatidia expressing Hth is reduced to normal levels in Apc2³³ mutants with two copies of an Apc2 transgene, P[Apc2^13.5]. (E) Average number of second row ommatidia expressing Hth for each genotype. Standard errors are shown. (F) Adult eye section from the dorsal-most retina of a homozygous Apc2³³ mutant. Ommatidia with a DRA fate are found above the solid white line and are characterized by inner photoreceptors with enlarged rhabdomeres (green arrowheads). There is an increased number of ommatidia with a DRA fate when compared to wild-type retinas (see Fig. 3C). (G) Schematic of the retina in wild-type, Apc1 mutant and Apc2 mutant flies. Loss of Apc1 induces apoptosis of all photoreceptors (orange). Loss of Apc2 causes an expansion of the DRA fate (pink).