Fig. 3. Defects in the optic placode following DE-cadherin loss of function and overexpression. (A,B) Anti-Crumbs, labeling apical membrane of ectodermal cells. Stage 15, lateral view of wild-type embryo (A) and shg^IH mutant (B). Note invaginated optic lobe (ol) attached to basal brain surface (br) in wild-type. In the mutant, the optic placode does not invaginate and remains at the surface. Placode cells lose contact and dissociate, as evidenced by reduced and patchy Crumbs expression. (C,D) Anti-FasII, labeling Bolwig’s organ (Bo) and posterior lip of optic lobe (ol). Stage 15, lateral view of wild-type (C) and shg^IH mutant (D). In wild type, Bolwig’s organ has separated from optic lobe and differentiated as photoreceptor neurons with axons staying attached to optic lobe. In shg mutant, cells of optic lobe and Bolwig’s organ still express the marker FasII but do not differentiate structurally. (E,F) Anti-FasII, stage 15, lateral view of embryo in which (E) heatshock mouse E-cadherin (hs-ME-cadherin^4b) and (F) Drosophila full length DE-cadherin (UAS-DE-cadherin^5,9) construct is expressed by da-Gal4. Cells of optic placode maintain their epithelial shape but do not invaginate. Bolwig’s organ does not separate from optic lobe.