Experimental scrapie in mice: Ultrastructural observations


  • Dr. J. Richard Baringer,

    MD, Corresponding author
    1. Departments of Neurology and Pathology, Veterans Administration Hospital, San Francisco, CA
    • Neurology Service (127), Veterans Administration Hospital, 4150 Clement St, San Francisco, CA 94121
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  • Stanley B. Prusiner

    1. Departments of Neurology and of Biochemistry and Biophysics, University of California, San Francisco, CA
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Scrapie, kuru, and Creutzfeldt-Jakob disease are characterized by a similar spongiform pathology, prolonged incubation periods, and an agent with unique physical, chemical, and biological properties. Swiss mice were inoculated with the scrapie agent and sacrificed three to five months later for light and electron microscopy. At three months, small vacuoles were seen within the neuropil of the cerebral cortex and basal ganglia. By the fifth month these vacuoles had increased in number and size and were accompanied by moderate astrocytic proliferation. The brainstem, cerebellum, and spinal cord showed variable changes of much less intensity. Many dialted postsynaptic processes contained osmiophilic particles in random or crystalline arrays. The particles, measuring approximately 23 nm in diameter, appeared consistently in postsynaptic processes of brain from scrapie-infected mice, were lacking in controls, and were of a size consistent with sedimentation and filtration data for the scrapie agent. Whether these particles represent the scrapie agent must await further studies.