CB1R immunoreactivity is absent in the upper small-intestinal epithelium of conditional intestinal epithelium-specific CB1R-deficient mice. When compared to control mice (a, IntCB +/+), conditional intestinal epithelium-specific CB1R-null mice (b, IntCB1−/−) are deficient in immunoreactivity for CB1Rs in the upper small-intestinal epithelium. Wild-type C57BL/6Tac mice display immunoreactivity for CB1Rs in the upper small-intestinal epithelium (c, WT (+)), which is absent when the primary CB1R antibody is not included (d, WT(-)). White arrows point to representative red immunoreactivity for CB1Rs. Red = CB1R immunoreactivity; blue = DAPI. WT = wild-type mice. (+) = with CB1R primary antibody; (-) = without CB1R primary antibody.