(a) Low power magnification electron micrograph in which the neoplastic cells remain barely attached by a few poorly developed junctions. The nuclei of both the cells in the center of the figure are moderately irregular and contain a single (right) or multiple (left) large nucleoli. (b) Detached multinucleated tumor cell in which the entire surface of the cell membrane is covered by microvilli. (c) A neoplastic cell with a markedly irregular nucleus containing a nuclear pseudoinclusion that is composed of cytoplasm showing partially degenerated organelles. The cell membrane appears to be covered by numerous microvilli. (d) Portion of a neoplastic cell showing numerous bundles of intermediate filaments located mainly in the paranuclear area. (e) Neoplastic cell showing intracytoplasmic lumina. The cell membrane that borders the intracytoplasmic lumina is covered by numerous, long, slender microvilli. (f) Neoplastic cell with intracytoplasmic lumen containing electon-dense material that probably represents proteoglycans. ((a). × 2000; (b). × 2000; (c). × 2000; (d). × 8500; (e). × 7000; (f). × 6000).