Central-peripheral distal axonopathy in the spontaneously diabetic BB-rat: ultrastructural and morphometric findings.

Central sensory nerve fibers were examined at distal (C3) and proximal (D12) levels of the gracile tract in the spontaneously diabetic BB-rat. Ultrastructural findings included early occurring malorientation of axoplasmic neurofilaments, axonal sequestration by honeycombing, and ensuing progressive axonal atrophy followed by Wallerian degeneration. Quantification of qualitative findings revealed a proximal to distal gradient in severity. Morphometric analysis confirmed a progressive myelinated fiber atrophy, which was more severe at the distal level. These findings are similar to those earlier described in peripheral sensory nerves of this model. Taken in concert with these previous findings, we conclude that the distal mainly sensory polyneuropathy in the diabetic BB-rat can be classified as a central-peripheral distal axonopathy.