Ultrastructural Relationship between Lewy Bodies and Pale Bodies Studied in Locus Ceruleus Neurons of a Non-Parkinsonian Patient

The Lewy body (LB) is a hallmark of Parkinson's disease (PD). The pale body (PB) also represents a characteristic intracytoplasmic alteration of the neurons of the substantia nigra and locus ceruleus of PD patients. We recently had the opportunity to study a non-parkinsonian patient (a 66-year-old man) who had numerous LBs and PBs in the neurons of the locus ceruleus. However, there was no evidence of neuronal loss in this region. We performed a detailed ultrastructural study of these inclusions for which multiple serial sections were used. Our results revealed that the constituent filamentous structures of the LBs and PBs were indistinguishable from each other, that transitions occasionally occurred between PBs and LBs, and that presynaptic structures entrapped in the cytoplasm were frequently present in the vicinity of both types of inclusion bodies. These findings suggest that PBs, at least those of the present type, actually represent early LBs. In addition, the entrapment of presynaptic structures by the cytoplasm of neurons of the locus ceruleus may indicate the existence of certain degenerative (or regressive) processes in these cells and that postsynaptic areas in particular, may have a role in PB and LB formation.