[Ultrastructure of human oligodendroglioma].

Ten cases of human oligodendroglioma were examined with electron microscope. The materials were specimens derived through surgical operations. Results were as follow. The shape of tumor cells are various, round, oval, polygonal and irregular. The majority of tumor cells have round or ovoid nuclei, some have irregular nuclei or nuclear indentation. Chromatin distributions tend to clump. In the cytoplasm, there are commonly ribosomes, rough surfaced endoplasmic reticulums, mitochondria, microtubules and lysosome. Glial filament is rare or almost absent. Crystalline structures are seen in 3 cases. Cellular junctions, though immature, are seen in 4 cases. Perinuclear halo in the light microscopy was explained to be a fixation artifact in 10% formol. The samples, which were fixed in 2.5% cold glutaraldehyde and post-fixed in 1% osmium tetraoxide, did not show perinclear halo under the light and electron microscope. The specimen, which were fixed in 10% formol, were examined with electron microscope. Plasma membrane of the tumor cell was partly destroyed, intracytoplasmic organelles and matrix were also broken, and the cytoplasm was empty. It is confirmed in this study that empty cytoplasm represents the peculiar perinuclear halo in the light microscopy.