[The analysis of nuclear organizer regions of astrocytomas with various histologic malignancies]

Nucleolar organizer regions (NORs) correspond to the loops of DNA which encode the ribosomal RNA. Acid proteins related to NORs can be stained by the silver colloidal technique (AgNORs). Since the configurations of AgNORs may be related to the protein metabolism or the proliferative activity of the cell, we tried to evaluate the corelationship between the morphology of AgNOR and the histologic malignancy in astrocytic tumors. For the quantitative evaluation the histographic pattern of AgNORs was analysed. Twenty-seven surgical specimens of astrocytomas (astrocytoma; 7 Cases, anaplastic astrocytoma; 9 cases, glioblastoma; 11 cases) were examined. The average of the means of AgNOR count in astrocytoma, anaplastic astrocytoma, glioblastoma were 1.68, 1.85 and 2.76 respectively. The averages of standard deviations (S. D.) of AgNOR count were 0.87, 1.03 and 1.26, respectively. In those tumors, the AgNOR histograms were flattered and the means and S. D. increased significantly as the malignancy increased. We speculate that the increased number and variations of AgNOR count could be a reflection of phenotypic alterations of astrocytoma cells such as cellular anaplasia and pleomorphism.