MOR and GPR177 colocalize within mouse striatum. Region of the striatum selected for immunohistochemical analysis is shown in the inset of Panel A. (A-C) Confocal images of immunolabeling of GPR177 (red) and MOR (green) within striatum. Arrowheads in A indicate GPR177 immunolabeling; arrowheads in B indicate MOR immunolabeling; arrowheads in C (merged image) indicate colocalization of the two proteins. Thin arrows (A and C) indicate a cell expressing only GPR177, whereas thick arrows (B and C) indicate a cell expressing only MOR. Arrows in lower left corner of panel A indicate dorsal (D) and lateral (L) orientations. Scale bar = 0.05 μm. (D) Electron photomicrograph showing immunogold-silver (GPR177; arrowheads) and immunoperoxidase (MOR; arrows) labeling within a dendritic process in mouse striatum. An unlabeled terminal (ut) forms a synaptic contact with a dendrite double-labeled for GPR177 and MOR (MOR-d). Scale bar = 50 μm. (E-F) Electron photomicrographs showing dual immunogold-silver-labeled GPR177 (arrowheads) and MOR (arrows) within a perikaryon (E) and dendrite (F) within mouse striatum. Scale bar = 0.5 μm. er: Endoplasmic reticulum; Nu: Nucleus; m: Mitochondria.