The astrocytic nature of glioblastoma demonstrated by tissue culture.

Forty-eight cerebral astrocytomas and glioblastomas were studied by tissue culture for two purposes: (a) the establishment of a definite growth pattern of cerebral astrocytomas and (b) the comparison of this growth pattern and that of glioblastomas. According to the grade of malignancy the series was divided into four groups: low-, middle-, and high-grade astrocytomas and undifferentiated glioblastomas. All the astrocytomas showed the same growth pattern with two successive phases. First, bipolar cells in radial arrangement emigrated from the explant, whereas in the last weeks, multipolar astrocytic-like cells in reticular arrangement predominated. The more malignant the cases, the more prolonged the bipolar phase, with retardation of the development of multipolar cells. Glioblastomas showed the same behavior with maximal persistence of the bipolar phase. On this basis, we believe that (a) cerebral astrocytomas have a characteristic behavior in vitro and (b) the glioblastoma is an astrocytic tumor showing maximal dedifferentiation.