Fig. 4. Distribution of anti-synapsin-positive (ASP) structures within the salivary gland. Whole-mount preparations of salivary glands were costained with anti-synapsin (red) and BODIPY-FL phallacidin (blue) and imaged by confocal microscopy. (A–F) A series of confocal sections through an acinar lobule. Each image shows the sum of 8 consecutive optical sections (inter-section distance: 0.45 µm) representing a total thickness of 3.6 µm. (A) The sum of all confocal images. The P-cells are arranged in pairs and their apical arrays of phallotoxin-stained microvilli appear as `bow ties' (asterisks). The C-cells are identified by short phallotoxin-labelled microvilli (E,F, open arrows) on their luminal surface. Rows of ASP foci (arrowheads) reside on the surface of the acinar tissue, next to P-cells (B), and extend deep into the acinar tissue, residing amongst C-cells (E,F). (G) Nerves interconnecting adjacent acinar lobules contain rows of ASP foci (arrowheads) and axons with homogeneous labelling for synapsin (arrows). (H,I) A small salivary duct (H) and a large efferent duct (I) with ASP foci (arrowheads) on the surface of the epithelial layer. Arrows indicate autofluorescent tracheoles. (J,K) Horizontal sections through a small duct (J) and a large duct (K) demonstrate that the ASP foci also reside within the duct epithelium, between the apical surface covered with phallotoxin-labelled microvilli (broad arrows) and the basal surface (broken line). Scale bars, 25 µm (A–I); 10 µm (J,K).