Fig. 5. Activation of Arm signaling leads to a morphological defect in photoreceptor length. (A) Horizontal section from a wild-type adult eye. Photoreceptors extend from the base to the apical surface of the retina. (B,C) Cross-section of wild-type adult retina. Most photoreceptors are present at the apical surface (B) and basal surface (C) of the retina. (D,E) Apical (D) and basal (E) cross-sections of an Apc1^Q8 retina containing a large clone of cells homozygous mutant for grim, reaper and hid (Df(3L)H99). (F-H) In eyes expressing constitutively active Arm^S10 under the control of a GMR-GAL4 driver, photoreceptor length is shortened (horizontal section in F, apical cross-section in G and basal cross-section in H).