IDH1 and oligodendroglioma: Next, we studied the cell-population composition in astrocytomas, IDH-mut, grade 3, and in oligodendrogliomas, IDH-mut, grade 3, without the necrosis and vascular endothelium proliferation, using flow cytometry, and compared the results with diffuse gliomas, IDH-mut, grade 2, as discussed above (Figure 2a).