Fig. 6. Vg and Notch upregulate cpa transcription in the wing blade primordium. (A-F') Third instar wing imaginal discs. (A,B,D-F) Standard confocal sections. (C) Optical cross section, stained with anti-Arm to outline the apical membrane. Clones are positively labeled with GFP (green in D',E',F'). (A,C,D,D';E,E') cpa antisense probe to reveal cpa mRNA expression (white in A,C,D,E and magenta in D',E') in wild type (A,C) or in clones overexpressing vg (white arrow in D,D') or in clones overexpressing N^intra (white arrow in E,E'). As cpa mRNA accumulates on the basal surface of the wing disc epithelium, standard confocal sections fail to reveal cpa accumulation in all vg and N- overexpressing clones. (B) cpa sense probe: the background level is very low. (F) Clones overexpressing N^intra, stained with anti-Vg (white in F or magenta in F'). Vg is misexpressed.