Figure 1.

Tumor cells of high‐grade oligodendroglial tumors with favorable prognosis resemble CD133^‐ lineage‐restricted progenitor cells. A. The in vitro growth pattern of tumors with favorable prognosis was analyzed after 7 and 21 days. Representative photographs are shown. B. Tumor spheres in high‐grade oligodendroglial tumors with favorable prognosis did not grow infinitely. The relative average sphere size of representative tumors with favorable prognosis (R24, R42, gray bars) as compared with primary GBM lacking an oligodendroglial component (R28 and R44, black bars) is given. Sphere size was determined weekly (DIV = days in vitro). C. Cells within spheres differentiated almost exclusively into GalC (Galactocerebrosid C, oligodendroglial marker) and βIII‐tubulin positive (neuronal marker) but barely GFAP‐ (glial fibrillary acid protein, astrocytic marker) or nestin‐expressing cells (stem cell marker). A representative differentiation profile is shown.