Fig. 5. Disp is required for the apical Hh-Np LPS formation in the wing imaginal disc. (A-C) Wild type, (D-F) disp, (G-I) yw hs-flp; enGAL4/UAS-Hh-Np; FRT82 hh^AC/FRT82 tubGAL80 and (J-L) yw hs-flp; enGAL4/UAS-Hh-N; FRT82 hh^AC/FRT82 tubGAL80 imaginal wing discs stained for Ptc (red in A-C,G-L) or Arm (red in F) and Hh (green). (C,F,I,L) Confocal z-sections corresponding to the level of the broken line in A,B,H,K. (H,K) Enlargements of the discs shown in G,J, respectively. (A-C) In wild-type discs, Hh-Np is secreted from the P compartment and forms apically located accretions (thin arrows in A and C) that can also be observed in anterior cells. In the first two or three rows of A-responding cells, larger intracellular accretions containing Hh and Ptc can be observed (thick arrows in B and C). (D-F) None of these accretions is observable in Disp mutant discs. Posterior hh-null clones expressing Hh-Np and abutting the AP border stimulate Ptc overexpression across a six- or seven-cell wide area (G-I), while clones of similar size expressing Hh-N activate Ptc in only three or four rows of cells (J-L). In both cases, small clones also appeared in the A compartment close to the AP boundary (arrowheads in H and K), most probably owing to engal4 expression in this domain at late larval stages. Although in hh^null UAS-hh-Np expressing clones Hh is enriched at the apical side (I) [as is endogenous Hh-Np (C)], in hh^null UAS-hh-N expressing clones, Hh is enriched basally (L). In the latter case, we observed very basal Ptc-Hh accretions (thick arrows in L), whereas in the former case Ptc-Hh vesicles are concentrated more apically in the receiving cells (thick arrows in C,I). In all cases, Hh-Np LPSs are observable, probably owing to the surrounding wild-type cells (thin arrows in I and L).