The intranuclear filamentous inclusions of a human glioma. Their relation with nuclear bodies

The intranuclear filamentous inclusions of a human glioma were analysed with an electron microscope equipped with a goniometer stage. The inclusions consist of 6 to 8 filaments. Considering the organization of the constituent filaments we distinguish three basic types: 1. Filamentous bundles of more or less parallel filaments, forming a cigarshaped inclusion. 2. Crystalloid inclusions: a. Prisms. They consist of stacked layers of strictly parallel filaments. The angle formed by the filaments of adjacent layers if 60 degrees. b. Cylinders. The layers of filaments are bent up and may form either a circle or a spiral, when the inclusion is seen in cross-section. 3. Partially crystalloid or "intermediate" inclusions. We consider them to be transitional forms between types 1 and 2 inclusions. The crystalloid layers of such intermediate inclusions may form either prisms or cylinders. Finally, the similarity between the granulo-fibrillar capsules surrounding granular nuclear bodies and filamentous inclusions, as well as the existence of granular material dispersed between the filaments of some inclusions led us to investigate a relationship between these two structures.