Localization of muscarinic 3 receptor in the walls of blood vessels in salivary glands. Fluorescent staining of CD31+/M3R+ blood vessels in representative sections from submandibular glands of (top) a BALB/c mouse and (bottom) a nonobese diabetic (NOD) mouse (Jackson Laboratories, Group 2). Images showing M3R+ staining (arrows) in the wall of CD31+ blood vessels (arrowheads). M3R+ acini cells (upper) and duct (lower) are also shown (arrows). Right images are merged. Scale bars = 50 μm. M3R, muscarinic 3 receptor; d, duct; v, vessel.