Fig. 2. Alkaline phosphatase domain in an intact adult D. melanogaster tubule pair: (A) control tubules subjected to alkaline phosphatase staining protocol without chromogenic substrate; the junction with the ureter is shown with an arrow; (B) DAPI-stained; (C) as in B but subjected to alkaline phosphatase staining protocol in the presence of NBT/BCIP chromogenic substrate; the junction with the ureter is shown with an arrow; (D) higher magnification to show predominantly apical localisation of staining. Scale bars, 100 µm for A-C, 10 µm for D.