Ultrastructure of eosinophilic inclusion bodies in the amygdala-parahippocampal region of aged squirrel monkeys treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, a dopaminergic neurotoxin.

Eosinophilic neuronal inclusions resembling cortical Lewy bodies have been observed in the amygdala-parahippocampal region of aged 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated squirrel monkeys. Electron microscopy in six monkeys revealed a composition of curving bundles of 16-17 nm filaments, arranged in a ball shape or as a cap adjacent to the nerve cell nucleus. The main difference between the monkey inclusions and human cortical Lewy bodies was the random orientation of the filaments in the human inclusion bodies.