Focal dendritic swellings in Purkinje cells in mucopolysaccharidoses types I, II and III. A Golgi and ultrastructural study.

Focal dendritic swellings in secondary dendrites of Purkinje cells were observed in post-mortem samples of the cerebellum processed by the Golgi method from three patients affected by mucopolysaccharidoses (MPS) types I-H, II and III. These focal dendritic swellings exhibited smooth surfaces but secondary formation of spine-like appendages was absent; in contrast, terminal, spiny branchlets were preserved. Complementary electron-microscopical examination of these samples revealed that membranous cytoplasmic bodies and zebra-like inclusions accounted for the material stored in these focal swellings in MPS I-H and MPS II; in addition, granulomembranous cytosomes with fine, densely-packed membranous profiles were encountered in MPS III. Focal dendritic swellings in Purkinje cells may result in abnormal electrical activity, thus producing informational imbalance on the Purkinje cell dendritic arborization in human mucopolysaccharidoses.