Fig. 2. Wingless spreads further when Rab5-dependent internalization is blocked. (A-C) Wg staining in single confocal sections of discs that expressed Rab5SN for 4 hours (A) or 5 hours 30 minutes (B,C) in the dorsal compartment. Apical, middle and basal sections are shown. Discs in A,B were stained using a protocol detecting both intra- and extracellular Wg; C shows extracellular Wg. (D) Single xz section perpendicular to the dorsal/ventral boundary of a disc 5 hours 30 minutes after the onset of Rab5SN expression. Dorsal Rab5SN-expressing compartment is to the right. The dorsal-ventral compartment boundary is indicated by a white line. Cadherin (green) marks apical junctions. Elevated Wg (red) accumulates apically at the level of and above junctions. Green arrows indicate junctions within the overlying peripodial membrane. (E) Single confocal section through the middle (8 µm below apical surface) of a wing disc that overexpressed GFP-Dlp for 24 hours in the dorsal compartment (indicated by brackets). The section passes through lateral cell membranes. Top: endogenous GFP-Dlp fluorescence. Bottom: extracellular Wg. GFP-Dlp overexpression elevates Wg on the lateral surface. Scale bar: 20 µm.