Ultrastructural findings in experimental Creutzfeldt-Jakob disease in guinea pigs.

Brains from six clinically ill guinea pigs from various serial passages infected with brain homogenate from a patient with Creutzfeldt-Jakob disease were studied by light and electron microscopy. There were no appreciable morphologic differences among the animals at different passages. Light microscopy revealed clearing, swelling, and vacuolar changes in neurons and astrocytes. These changes occurred in both perikarya and cell processes. Large isolated vacuoles in the neuropil appeared to develop by progressive fusion between swollen cellular processes. By electron microscopy many neuronal processes contained degenerating organelles, osmiophilic bodies, membranous bodies and approximately 10 mm filamentous structures. In addition, vacuoles and membranous inclusions were seen in some neuronal nuclei, changes which have not been previously observed in spongiform encephalopathies.