SK3 immunoreactivity in the healthy adult rat striatum. Confocal micrographs of coronal sections show salient features of the adult rat striatum, microglia/macrophages, and SK3 staining. A. A low-magnification image of the entire hemisphere (scale bar, 1 mm); the striatum is indicated by a dashed curve; V, ventricle; CC, corpus callosum. White matter is labeled with an antibody against myelin basic protein (MBP) (mouse monoclonal, 1:100) and a Cy3-conjugated secondary antibody (donkey anti-mouse, 1:400); note the dark 'holes' between the brightly stained axon bundles seen in cross-section. B. Diffuse SK3 staining is seen between the unstained white matter tracts (asterisks) in the normal striatum: co-labeled with FITC-conjugated tomato lectin (TL, 1:400), and anti-SK3 (rabbit polyclonal, 1:500) with a Cy3-conjugated secondary antibody (donkey anti-rabbit, 1:400); scale bar, 100 μm. Lack of non-specific staining is shown by the negative control (inset) with Cy3-conjugated 2° antibody alone. C. A high-magnification image (scale bar, 5 μm) shows intense SK3 staining in microglial processes (marked with arrows) and punctate staining elsewhere (labeled as above; and with the nuclear stain, DAPI).