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Cytochemical components of mitochondrial dense bodies in the brain in Menkes disease: Electron microscopic cytochemistry and X‐ray microanalysis
Author(s) -
Yoshimura Noriaki
Publication year - 1997
Publication title -
neuropathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.701
H-Index - 61
eISSN - 1440-1789
pISSN - 0919-6544
DOI - 10.1111/j.1440-1789.1997.tb00059.x
Subject(s) - cytochemistry , microanalysis , matrix (chemical analysis) , chemistry , lipofuscin , biophysics , electron microscope , staining , ultrastructure , biology , chromatography , anatomy , biochemistry , physics , genetics , organic chemistry , optics
Mitochondrial alterations, including mitochondrial dense bodies (MDB), are well known to occur in the brain in Menkes disease. Because their chemical components have not been revealed yet, we have examined them by electron microscopic cytochemistry and X‐ray microanalysis after routine electron microscopic observation. Routine observations demonstrated that the electron density deposit of MDB appeared to be medium to high, with a woolly and fine‐granular margin and no limiting membrane. The diameter of MDB ranged from 0.2 to 0.8 μm. The smaller MDB appeared as aggregates of matrix precipitates that were spherical or occasionally irregular in shape and sometimes indistinguishable from woolly densities. The larger MDB, mostly spherical, were also formed in close association with matrix precipitation and cristal membrane disintegration, which appeared to contribute to the growth of MDB. Treatment with an equal mixture of chloroform and methanol resulted in minimal extraction of the lipid component, so that the density of MDB was reduced only a little and the MDB became irregular in shape. In contrast, treatment with pronase or trypsin produced complete digestion of MDB. Electron microscopic periodic methenamine silver (PAM) stain demonstrated that MDB were positive for such staining. Electron probe X‐ray microanalysis revealed that there was no element accumulated in abnormally high concentrations in any MBD examined. These data indicate that MDB are composed of much protein, some saccharide and minimal lipid. The composition and morphology of MDB are most similar to woolly densities, which are known to be accumulations of denatured matrix substances plus disintegrated cristal membrane material of mitochondria in lethally injured cells. As the activities of copper enzymes, such as cytochrome oxidase and superoxide dismutase, are deficient in Menkes disease, increased peroxidation may be most responsible for MDB formation in the brain in this disease.