Laminated cytoplasmic bodies in Schwann cells and phagocytes: an ultrastructural and cytochemical study in the normal and lead-damaged peripheral nervous system of the rat.

We studied the distribution and cytochemical characteristics of laminated bodies (LBs) in the peripheral nervous system of normal and lead-intoxicated rats. In normal rats, LBs were exclusively present in myelin-forming Schwann cells (SCs). Nerves from lead-intoxicated animals showed extensive demyelination and remyelination. In these nerves we found an increase of LBs in the SC cytoplasm, and also within phagocytes involved in myelin removal, but not in remyelinating SCs. Cytochemical studies revealed that LBs were positive for acid phosphatase, thus demonstrating the lysosomal nature of such inclusions. Taken together, these data suggest that LBs are autophagolysosomes derived from myelin catabolism, which may be enhanced in the lead-induced demyelinating neuropathy of the rat. The possible mechanisms underlying this phenomenon and their pathological relevance are discussed.