<正> 8 specimens of meningioma（4 meningotheliomatous

3 fibrousand 1 transitional）were observed with transmission electron micro-scope（TEM）.The main feature of most tumor cells is that there aremany conspicuous interdigitations of cytoplasm protruding outfrom the cell surface.There are a lot of mitochondria

Golgi com-plexes and microfilaments which are closely packed or scatteredinside the interdigitations.Between the interdigitations

many des-mosomes are seen.The meningiomas have an epithelioid structure.which may explain why the tumors cells would not scatter outwhen the smear samples or histological sections are observed underlight microscope.The three types of meningiomas described inthe present work may mainly originate from epithelioid cells ofarachnoid granulations as inferred from the ultrastructure observed.We did not find any distinct differences in the ultrastructuresamong them.