ULTRASTRUCTURAL INVESTIGATION OF DNA IN MEGAKARYOBLASTIC LEUKEMIA BY USING OSMIUM-AMMINE-B - COMPARISON WITH SEVERAL TYPES OF LEUKEMIA

Using DNA staining with highly stable osmium-ammine-B, the blasts of A MKL were observed under an electron microscope, in comparison with AML , ALL, CML-MK crisis and TMD. The DNA within the nucleus of the megaka ryoblasts was observed as a high electron-density substance and tended to be uniformly dispersed within the nucleus. DNA, associated with nu cleoli, could be roughly divided into four types based on the presence or absence of peri-nucleolar clumps and intra-nucleolar clumps. In ca ses of AMKL, we often observed a type that did not have peri-nucleolar DNA clumps but did have DNA flecks within the nucleoli. By analytical evaluation there were no differences among cells from several subtype s of megakaryocytic leukemia, such as AMKL in children with Down's syn drome, AMKL in children without Down's syndrome, AMKL in adults, and C ML-MK crisis. The DNA distribution of TMD blasts, which were self-limi ted and not malignant, resembled that of AMKL blasts.