Triple immunofluorescence for NR2 (green), NOS-1 (red), and PSD-95 (blue). A, CA1 pyramidal cells express all three proteins. NR2 stains somata and proximal dendrites, although puncta in the neuropil are also visible; staining for PSD-95 is almost exclusively punctate, and NOS-I shows an intermediate staining pattern.B, High-magnification views of the material shown in A reveal that some spines visible with NR2 staining label also for both PSD-95 and NOS-I (arrowheads). Triple-stained puncta are also visible in the neuropil (arrow); however, in this material, it is impossible to determine whether these puncta are associated with dendritic spines. Contrast is enhanced in thebottom panel to facilitate identification of multiple labeling. Scale bars: A, 50 μm; B, 3 μm.