[The ultrastructure of a gangliocytoma (author's transl)].

The tumor tissue removed surgically from the left parietal subcortical area of a 16-year-old boy was studied by light and electron microscopy. Our results were identical to cases reported previously. By light microscopy, the neoplasm was composed mostly of mature and immature ganglion cells and glial cells. Ganglion cells with large nuclei and prominent nucleoli had characteristic Nissl substance in various amounts and they were encompassed in a network of fibrous connective tissue. Glial cells were mainly oligodendrocytic. Astrocytes were small in number and did not show neoplastic growth. By electron microscopy, mature ganglion cells contained dense core vesicles in their cytoplasm and processes. The size of the vesicles ranged from 100 to 200 nm. Furthermore ganglion cells were surrounded by their own processes and also processes of glial cells. Ganglion cells were rarely found in synaptic contact with adjacent processes. Instead, oligodendrocytes were sometimes situated adjacent to these ganglion cells. These findings suggest that the tumor under study may be of hamartomatous origin. Aside from mature ganglion cells and glial cells, immature cells were present. From viewing the architecture of these immature cells, we concluded that they were also ganglion cells.