Ultrastructural pathology of axons and myelin in experimental scrapie in hamsters and bovine spongiform encephalopathy in cattle and a comparison with the panencephalopathic type of Creutzfeldt-Jakob disease.

We report the ultrastructural pathology of axons and myelin sheaths in bovine spongiform encephalopathy (BSE) and experimental scrapie in hamsters and compare it with that found in a panencephalopathic model of Creutzfeldt-Jakob disease (CJD). Intramyelinic vacuoles (myelin ballooning), dystrophic axons, phagocytic astrocytes and macrophages were found in all three models but to different degrees, while axons containing numerous cellular processes and concentric cisterns were observed only in experimental scrapie and CJD. We conclude that axonal and myelin pathology is a widespread phenomenon and the differences between panencephalopathic CJD and polioencephalopathic BSE and scrapie are only quantitative.