Histological and magnetic resonance analysis of sciatic nerves in the tellurium model of neuropathy

Ingestion of tellurium (Te), a toxic element, produces paralysis of the hind limbs in weanling rats that is due to temporary, segmental demyelination of the sciatic nerves bilaterally. Weanling rats were fed a 1.1% elemental Te diet and sacrificed at various time points for histological and magnetic resonance (MR) analysis of the sciatic nerves. No controls exhibited impairments of the hind limbs, whereas Te-treated animals became progressively impaired with increased Te exposure. Toluidine blue-stained nerve sections of Te-treated animals showed widened endoneurial spaces, disrupted myelin sheaths, swollen Schwann cells, and a few instances of axonal degeneration. Te decreased healthy myelin by 68% and increased percent extracellular matrix by 45% on day 7. MR experiments showed a decrease in the area of the short T-2 component, an increase in average T-1, and an increase in the position of the intermediate T-2 component in Te-treated nerves. The correlation coefficient for healthy myelin and average T-1 was 0.88 and that for healthy myelin and the area underneath the short T-2 component was 0.77. The area of the short T-2 component has been postulated as the best measure of the process of demyelination.