Figure 9.

Distribution of dopaminergic fibers on salivary ducts, the reservoir, and the reservoir muscle Summarized views of confocal image stacks through whole-mounts double-labeled with anti-dopamine (red) and BODIPY FL phallacidin (blue). The upper left inset presents a scheme of the various structures examined and outlines the areas shown in a-j. Asterisks in a,c,d,i indicate acinar tissue. a: Small salivary ducts (broad arrows) are mostly without dopaminergic fibers (long arrow). b: A small salivary duct without dopaminergic innervation at higher magnification. c: A dopaminergic fiber approaches a small salivary duct and terminates on the duct surface (arrowhead). d: A dopaminergic fiber (arrow) invades the epithelium of a small duct. A vertical section (inset) through the duct at the position indicated by the line in d demonstrates that the dopaminergic fiber (arrow) resides below the duct surface (broken line). e,f: Dopaminergic fibers (arrows) form a loose network on a large salivary duct and terminate on this structure (arrowheads). The inset in f shows a horizontal confocal section through the duct and visualizes a dopaminergic fiber within the duct epithelium, below the duct surface (broken line). g: The salivary nerve coming from the subesophageal ganglion and extending along the reservoir/salivary duct complex contains a single thick dopaminergic axon. h: On the reservoir duct, small dopaminergic varicose fibers reside superficially within the salivary nerve (arrows) or leave the nerve and extend over the duct surface. i: A loose network of dopaminergic fibers with fiber terminals (arrowheads) covers the reservoir. j: Dopaminergic fibers and terminals (arrowheads) within the reservoir muscle. White scale bars = 100 μm; yellow scale bars = 25 μm