An electron microscope study of reacting astrocytes in gliomas induced by N-ethyl-N-nitrosourea in rats

Summary

The fine structure of reacting astrocytes in experimental gliomas has been described. These tumours were induced transplacentally by 30 mg of N-ethyl-N-nitrosourea per kg of body weight injected into the tail vein of pregnant BD-IX rats on the 15th day of gestation. In tumour-bearing animals astrocytes undergo striking morphological changes and show increased mitotic activity. Reacting astrocytes around gliomas display large, eccentric, irregular nuclei and the abundant cytoplasm contains an increased number of cell organelles. The most dramatic increase is in glial filaments: these form thick bundles at the periphery of the cells and in the processes which are frequently seen around demyelinated axons. Reacting astrocytes engulf and break down myelin sheaths: their remnants, lamellar inclusion bodies and lipid droplets, are present in the cytoplasm. Extravasated erythrocytes are also surrounded by and digested in reacting astrocytes. Numerous lysosomes could provide the necessary enzymes for the phagocytic activity of these cells.