Intranuclear Paracrystalline Fibrillar Arrays in Human Glioma Cells

Summary Characteristic paracrystalline fibrillar arrays, some of which displayed interfilamentous septa, were found in the nuclei of human astrocytoma and glioblastoma multiforme cells. In astrocytoma, they were composed of bundles of linear filaments, each about 70 A thick, oriented in a regular spacing of about 300 A in periodicity. Others exhibited periodicity of approximately 170 A. These figures had a diameter of about 40 A. Some filaments appeared to separate into two parallel components that sandwiched a clear layer, and others consisted of a linear arrangement of short filaments at regular intervals. In addition, a few of them showed small particulates, possibly cross-sections of filaments, which were regularly oriented in a linear array. In glioblastoma multiforme, filaments about 60 A thick were regularly arranged with a periodicity of around 200 A. The paracrystalline fibrillar arrays were closely associated with the fibrillar components of the nuclear bodies in glioblastoma multiforme and usually were associated with free lipid droplets in astrocytoma. On the other hand, lipid droplets as well as nematosomes, tubular structures, and flocculent materials were found in the widened perinuclear gap in the nuclei of astrocytoma cells. In the latter sites, they were surrounded by the inner nuclear membrane alone. On the basis of electron microscopic observations of the nuclei of human glioma cells, two possible origins of the intranuclear paracrystalline arrays might be considered.