Organization of the Midgut Junction Region. A) Schematic of the organization of the midgut junction region. Extensions of the longitudinal muscles (red stripes) of the gastric caeca attached to the midgut junction region which contain two groups of enteroendocrine cells, the Midgut Junction DH31 expressing cells (in green) and cholinergic Allostatin B/MIP expressing cells(mauve outlined/red). The lumen of this region of the gut is thinner when compare to the remainder of the midgut and acts like a valve (in orange). This region of the midgut is a conspicuous bent and twisted before the entry into the acidic region. B) Model of the regulation of peristalsis in the midgut. Midgut Junction DH31 expressing cells secrete DH31 basally to stimulate contractions. This secretion may be stimulated through the atypical ACh paracrine-like signalling from neighbouring Allostatin B/MIP secreting enteroendocrine cells. An unidentified reciprocal signal may emanate from the Midgut Junction DH31 expressing cells to regulate the expression of Allostatin B/MIP or ACh.