[Ultrastructure of human cerebral neoplasms in vitro: medulloblastoma].

The fine structure of five lines of medulloblastoma cells in long-term cell cultures are described. The cell cultures were fixed in situ by the rapid exchange of the medium for the fixative solution consisting of 3% glutaraldhyde in 0.1 M Na cacodylate-HC1 buffer with 0.1 M sucrose (pH 7,2, total osmolality 510 mOsm, vehicle osmolality 300 mOsm). The cultures were subsequently postfixed in 1% OsO4 in water at room temperature and dehydrated in a graded series of ethanol solutions. In the second change of 100% ethanol they were stained with 2% uranyl acetate for 10 minutes. They described the structural characteristics of these cells in relation to the various phases of the culture, is similar to the well known of in vitro cellular embryonal systems (spongioblasts).