[Ultrastructural study of the growth pattern in an experimental meningeal gliomatosis model].

We tried to examine the growth pattern of meningeal gliomatosis (MG) by using an experimental MG model. C6 rat glioma cells (3 X 10(5)/0.1 ml) were injected percutaneously into the cisterna magna of rats. Seven days after inoculation, the brains and spinal cords were removed and processed for morphological observation. Light microscopic findings showed that numerous tumor cells had invaded the spinal cord parenchyma directly and/or via the Virchow-Robin spaces. In contrast, a small amount of tumor cells had spread horizontally on the surface of the spinal cord. By transmission electron microscopy, discontinuity of the basal lamina (of the marginal glia) was found, and some tumor cells were found to have protruded their processes into the spinal cord parenchyma. A basal lamina-like granular material was observed in the vicinity of these areas, indicating the breakdown of the basal lamina. Scanning electron microscopic findings further supported the speculation concerning the penetration of the pia mater by tumor cells through the small pores which had blunt margins. From these ultrastructural observations, we speculated that some chemical membranolytic factors might play an important role in MG.