The fine structure of astroblastoma.

An astroblastoma in the cerebrum was investigated with the electron microscope. A distinctive feature of the tumor was the radial arrangement of astrocytic cells around the blood vessels. The blood vessels in the tumor commonly exhibited fenestrated endothelial cells. The endothelium was generally surrounded by lamellated basal laminae that were compactly invested in the neoplastic cells. The most remarkable feature of the tumor cells was the frequent presence of coated vesicles. The cytoplasm of some tumor cells was filled by delicate glial fibrils and microtubules, whereas that of others contained a moderate amount of rough-surfaced endoplasmic reticulum, free ribosomes, and mitochondria, but only scanty glial fibrils and microtubules. The former usually possessed long, thin cell processes, whereas the latter had poor development of cell processes and commonly showed multiple or giant nuclei containing several nuclear bodies and prominent nucleoli. In summary, this ultrastructural study of astroblastoma revealed the coexistence of varied maturity astrocytic cells and their compact arrangement around fenestrated blood vessels.