Figure 5. FMRFamide-like immunoreactivity (FLI) in the foregut and midgut of Phormia regina. A) Diagram showing FLI in the gut of P. regina. FLI occurs in the retrocerebral complex (RCC), crop duct nerve (CDN), and on the proximal surface of the crop sac (C) of the foregut. In the midgut, FLI occurs in nerves running down the dorsal surface of the anterior midgut and in numerous midgut endocrine cells of the posterior midgut. B) FLI processes from the crop duct nerves ramify out into a fine network on the proximal surface of the crop sac (arrows). C) FLI midgut endocrine cells of the posterior midgut. Open-type endocrine cell morphology (apical processes projecting toward lumen) is evident in many cells (arrow). E, esophagus; PV, proventriculus; CD, crop duct; MT, Malpighian tubules.