Figure 9. FMRFamide-like immunoreactivity (FLI) in the foregut and midgut of Tabanus nigrovittatus. A) diagram showing FLI in the gut of T. nigrovittatus. In the foregut, FLI occurs in cells at the junction of the foregut and the midgut, in the crop duct nerves, and on the proximal surface of the crop sac of the foregut. In the midgut, FLI occurs in nerves running along the surface of the anterior midgut and in the midgut endocrine cells of the posterior midgut. FLI in the anterior and posterior midgut of T. nigrovittatus. B) The entire surface of the anterior midgut is covered by a fine plexus of FLI fibers. Two large FLI nerves emanating from the region of FLI cells and processes at the foregut/midgut junction run posteriorly on the dorsal surface of the anterior midgut. FLI nerves originating from this same region run down the crop duct (CD). C) FLI midgut endocrine cells in the posterior midgut. FLI midgut endocrine cells exhibit open-type endocrine cell morphology and form a dense ring around the terminal end of the midgut, just anterior to the pyloric sphincter. GC, gastric caecum; MG, midgut; E, esophagus; PS, pyloric sphincter; CDN, crop duct nerve; C, crop; MT, Malpighian tubules; HG, hindgut.