Aggregations of 35-nanometer particles associated with neuronal cytopathic changes in natural scrapie

Neuronal vacuolation and intravacuolar budding of vesicles and cytoplasmic processes appear to be the most characteristic cellular lesion in natural scrapie, a chronic degenerative disease of the central nervous system of sheep which is transmissible by injection. Membrane-bound accumulations of the 35-nm particles are fotnd in the cytoplasmic processes that project inside the vacuoles of the neuronal perikaryon. Such particles are present only in a small number of vacuolated neurons.