Fig 1: Extrinsic and intrinsic cholinergic innervation of the endocrine pancreas (figure adapted and modified from Supplementary Figures 4, 5 in Makhmutova et al, 2020). (A, A’) Mouse pancreatic section immunostained for the pan-neuronal marker PGP9.5 (green) and glucagon (red); scale bar 50 µm. (B, B’’) Pancreatic section of a Phox2b-Cre-tdTomatofloxed transgenic mouse, immunostained for red fluorescent protein (red), the sensory neuronal marker substance P (SP, green), and the cholinergic neuronal marker vesicular acetylcholine transporter (vAChT, blue). Inside the neuroinsular ganglion, Phox2b-positive varicosities colocalize with vAChT (B’, arrows), indicating terminals of vagal preganglionic neurons; scale bar 20 µm. Outside of the neuroinsular ganglion (inside the islet), Phox2b-positive fibers colocalize with SP (B”) but not with vAChT (B’, asterisks), indicating vagal origin of sensory fibers and non-vagal origin of intrinsic cholinergic fibers; scale bar 5 µm.