Electron-microscopic observation of the nucleus basilis of Meynert in human autopsy cases

The large neurons of the nucleus basalis of Meynert (nbM) were examined with the electron microscope in 13 autopsied human adults. The neurons were characterized by a prominent Nissl substance and accumulation of lipofuscin granules. Lamellar bodies were often observed among the Nissl substance. Many of the lipofuscin granules were large and had a characteristic pronounced mosaic pattern of pale areas within gray zones. Menbranous structures within the nucleus and periodic transverse processes in the cristae of the mitochondria were regarded as postmortem alterations. Alzheimer's neurofibrillary tangles (NFT) were observed in two cases. Intranuclear fibrillary bundles were identified in four cases. Crystalloid formation in rough endoplasmic reticulum was identified in two cases. Hirano body was observed in a case of parkinsonism with dementia. Axonal swelling was seen in three cases and interpreted as axonal dystrophy, an age-related phenomenon. A basal body, which is unusual in neurons of the central nervous system (CNS), was observed in one case. Lewy bodies were observed in a case of parkinsonism.