Immunohistochemistry (Set A, contiguous sections): ED-2+ and PB+ macrophages (arrows) were identified within the meninges, choroid plexus, and perivascular locations [colocalized images, 20×, scale bar = 25 µm]. Brown = ED-2+, Blue = PB+, Background = nuclear fast red counterstain. Immunofluorescence (Set B, contiguous sections): These ED-2+ and PB+ macrophages, located at the interface between the blood-brain barrier and the extravascular space, were found to express both MHC-II complex and TNF-α [colocalized images, 40×, scale bar = 25µm]. Blue = DAPI for nuclei. Red = Rhodamine for ED-2/MHC-II. Green = FITC for TNF-α.