Fig. 4. Role of ß-catenin in optic placode morphogenesis. (A) Invaginating optic placode of stage-13 wild-type embryo, labeled with anti-Crumbs. (B,C) Rudimentary optic placode of arm¹; arm^s14 embryo (B) stage 13 labeled with anti-Crumbs and (C) stage 16 using anti-Fasll to label optic lobe (ol) and Bolwig’s nerve (Bn). The arm^s14 is a deletion construct of ß-catenin, which lack the -catenin binding domain. Arm^s14 is able to carry out Wg signaling function but not DE-cadherin-related function. Optic placode cells have dissociated into small, disjunct vesicles that fail to invaginate. (D) Anti-Fasll, stage 16, showing lack of separation of optic lobe and Bolwig’s organ in embryos expressing the fusion protein UAS-DE-cad--catenin under the control of da-Gal4. Other abbreviations: bo, Bolwig’s organ; br, brain.