Light, fluorescence, and electron microscopic features of neuronal intranuclear hyaline inclusions associated with multisystem atrophy.

Light, fluorescence, and electron microscopic features of intranuclear hyaline inclusions of neurons associated with multisystem atrophy in a 21-year-old woman are described. The neuronal inclusions resemble Marinesco bodies on light microscopy but differ from the latter in their distribution, autofluorescence, and ultrastructure. They are widespread in almost all central, peripheral, and autonomic neurons and are generally larger than Marinesco bodies. The inclusions emit yellow-green autofluorescence with ultraviolet light between 470 and 530 nm of the spectrum and are ultrastructurally composed of haphazardly arranged, uniform, fine, straight filaments (8-9 nm in diameter). The neuronal inclusions have neither the ultrastructural feature of known viral inclusions nor are associated with virus particles. Their chemical nature and pathogenesis remain to be elucidated.