[The fine structure of cell processes in astrocytoma (author's transl)]

Astrocytes, in normal tissue, may be characterized by their extensive processes which may be cylindrical in part but are sheet-like at their periphery where they serve to cover other structures. It becomes of interest ot determine the morphology of astrocytic processes after neoplastic transformation. We, therefore, examined the fine structure of 14 cases of astrocytomas. In general the fine structure of the cell bodies and the interior of the processes are fundamentally similar to those of normal or developing astrocytes. Differences are apparent at the cell periphery. These include less well developed cell junctions and usually only poorly formed peripheral expansions of the processes. Most sections through the processes appear round or oval rather than laminar in normal astrocytes. They often consist of small microvilli or pseudopodia-like protrusions. Whether these changes are due to the immaturity of the cell or to the lack of appropriate nearby target cells is not known.