Detection of PrPres and blood vessels in tg44 and C57 mice at 160 days after microinjection of RML scrapie. Sections show thalamus at a level 2–3 mm caudal to the needle track. Sections were stained with D13 to detect PrPres (red), with anti-CD31 to detect blood vessel endothelial cells (green), and DAPI (blue) to detect nuclei. (a) In tg44 mouse dense PrPres plaques appear to associate with CD31-positive vessels of various sizes. Two large veins (arrowheads) and several capillaries (arrows) are indicated. Erythrocytes in vessels show green autofluorescence. (b) In C57 mouse PrPres is diffuse and appears to be concentrated around possible neurons (arrows) with large DAPI- stained nuclei, rather than around blood vessels (arrowheads). Scale is same in each panel, and bar represents 50 μm.