Light and electron microscopic studies of the 139A-H strain of scrapie passaged in hamsters

We report here the light and electron microscopic neuropathology of the 139A-H strain of scrapie passaged in Syrian golden hamsters. The general neuropathological picture consisted of the spongiform change and severe astrocytic gliosis. The topography of prion protein (PrP) was variable, the highest signal was observed in the CA2-molecular layer, CA1-pyramidal and entorhinal cortex. The electron microscopy consisted of: 1. Spongiform vacuoles – these are always membrane bound and contain secondary vacuoles (i.e. membrane-bound compartments or vesicles within vacuoles) and curled membraned fragments. 2. Tubulovesicular structures (TVS) – these are vesicular structures of approximate 27 nm in diameter within neuronal processes – i.e. axonal terminal or dendrites. TVS are smaller and of higher electron density than synaptic vesicles. The significance of TVS remains unknown. 3. Dystrophic neurites. Dendrites or axonal preterminals and terminals filled with electron-dense bodies, including small autophagic vacuoles. 4. Apoptotic cell nuclei. 5. “Whorls”, concentric arrays of membranes were visible. A significance of those structures is unknown.