Ultrastructural studies of myeloma cells: observations concerning the Golgi apparatus and intermediate-size filaments.

Studies on the ultrastructure of tumor cells of 22 multiple myeloma patients revealed hitherto unreported observations concerning the Golgi apparatus and intermediate-size filaments. Various abnormalities of the Golgi apparatus including displacements of the Golgi stacks, dilatations of cisternae, and massive accumulations of vesicles as well as vacuoles in the Golgi region were found in myeloma cells of 11 patients. Intermediate-size filaments forming a fine intracytoplasmic network were apparent in myeloma cells of all 22 patients. In five patients, in addition to this architecture, intermediate-size filaments were gathered into thick bundles which were primarily but not exclusively located in the perinuclear region.