CHANGES IN SCHWANN-CELLS AND VESSELS IN LEAD NEUROPATHY

  • 1 January 1982
    • journal article
    • research article
    • Vol. 109  (2) , 193-205
Abstract
Transmission electron microscopy (TEM) of peripheral nerve in rats receiving 6% lead carbonate for 4-10 wk provided evidence of a specific Schwann cell injury, associated with demyelination. Intranuclear inclusions in Schwann cells appeared within 2 wk of administration of a Pb-containing diet. Swelling of Schwann cells and disintegration of their cytoplasm was evident at 4 wk. Distinctive electron-dense inclusions appeared in Schwann and endothelial cells during the intoxication and were ultrastructurally identical to pathognomonic inclusions of Pb poisoning seen in renal tubular epithelial cells. Scanning microscopy (SEM) with electron-probe microanalysis was used to identify the Pb-containing deposits. In addition to Schwann cell changes, vessels revealed endothelial cell injury and altered permeability to macromolecules. Since morphologic changes of Schwann cells preceded the development of altered vascular permeability and endoneurial edema, Pb gained access to the endoneurium prior to the development of altered vascular permeability, suggesting that edema and altered endoneurial fluid pressure were epiphenomena that supervened after demyelination occurred. Remyelination. Schwann cell proliferation and formation of onion bulbs were manifestations of persistent toxic injury to myelin-sustaining cells, resulting in chronic demylination.