Neuroaxonal and dendritic dystrophy in diabetic autonomic neuropathy. Classification and topographic distribution in...

Autonomic diabetic neuropathy in sympathetic nerves is characterized by the progressive development of an axonopathy and dystrophic changes. In the present study the dystrophic changes occurring in the diabetic BB-rat were further characterized. Based on their ultrastructural composition, they could be divided into five types; tubulovesicular (Tv), layered membrane (Lm), neurofilamentous (Nf), membranous body (Mb) and large branching tubular (Bt) types. The relative frequencies of the various types changed during the course of diabetes, with the Mb type being most frequent during the early course of the neuropathy, whereas the Tv and Nf types were more common during the late stage. The Mb and Tv types commonly terminated in growth cones and filopodia in the mesenteric nerve. The Nf type was common in proximal axons, dendrites and postganglionic perikarya, whereas the Bt type was only found in postganglionic dendrites. The chronologic development and topographic distribution of the various types of dystrophic changes suggest a diversified pathogenesis of these pathologic structures.