In 6 out of 7 autopsy cases of olivopontocerebellar atrophy, we found characteristic features of neuronal swelling degeneration (abbr. NSD) in the nerve cell of the substantia nigra. NSD was classified into 4 types according to the microscopic features. The cell body of the type A NSD is much larger than the usual nerve cell, contains melanin granules, is round in shape and appears granular. This cell sometimes contains a shrunken nucleus, Marinesco body, Nissl granules and rest of melanin pigment, suggesting its origin in the degenerating melanin containing nerve cell. In type B NSD the periphery of the swollen cell body appears to be frosted glass with a Nissl Substance. A part of the type B NSD was suggested to have its origin in the nerve cell which has no melanin pigment. Type C NSD is round or irregular in shape and appears to be vacuolar, suggesting its origin in the dendritic process. Type D NSD is sharply bounded from the surrounding tissue and amorphous structures. Judging from its staining characteristics, its origin was suggested to be in the axon. The significance and pathogenesis of the NSD are discussed with special reference to its relation to glutamic acid.
neuronal swelling degeneration