part of develops from midgut imaginal island adult midgut FBbt:00003141 adult ventriculus The middle region of the adult alimentary canal, the epithelium of which is lined with peritrophic membrane rather than chitinous intima as for the foregut and hindgut. The radius along the midgut is not uniform, with 6 major constrictions delimiting 6 regions (R0-R5). The anterior midgut (R1-R2) functions in absorption, the posterior (R4-R5) plays a role in reabsorption, and the middle acidic region (R3), which contains the copper cells (adult cuprophilic cell), in secretion and absorption. fly_anatomy.ontology mesenteron FBbt:00003138 midgut adult gut