In vitro growth of neoplastic rat glial cells.

An ependymoma was induced in the brain of a BD-IX rat by repeated doses of MNU. In vitro grown cells of the tumor were fibroblasts and stellate cells considered to be glial. Reimplantation of these cells into the brain of another BD-IX rat resulted a tumor growing in the meninges. This tumor was then repeatedly transplanted over several passages. Its gross morphology resembled that of a sarcoma; however, glial in cells could be demonstrated with silver methods. A cell line derived from the first transplanted tumor group proved to contain S-100 protein in traces in the first passages in vitro. Explanted cells of the primary ependymoma were cloned. Two clones were established, RGL 1 and RGL 2. The cells of both clones resembled morphologically the stellate elements of the primary explant. RGL 1 contained S-100 protein. It was cloned again in the 16th subpassage. Four clones were established. Only 1 contained S-100 protein in traces. The clone RGL 1 had a subdiploid karyotype with a modal number of 39 and a large submetacentric marker. It was subcloned in the 25th passage with two clones, both having a karyotype of 41 chromosomes.