The development of brain tumours produced in rats by the intracerebral injection of neoplastic glial cells: a fine structural study.

Tumours were produced by the intracerebral injection of a clone of glial cells derived from a glioma induced transplacentally by N-ethyl-N-nitrosourea in a BD-IX rat. The injection of 5 X 10(5) cells into the left frontal lobe resulted in a 100% incidence of tumours. To follow the development of the neoplasms, the brains were studied from 1 day to 4 weeks after injection. The tumours maintained their glial characters throughout, but their features changed with time. Ultrastructurally, they were pleomorphic: the proportion of fibrillary astrocytes, undifferentiated and intermediate cell types varied according to tumour size. When smaller (1 and 2 weeks), fibrillary astrocytes predominated, but when larger (3 and 4 weeks), the number of undifferentiated astrocytes considerably increased. A reproducible brain tumour model with a short latency has thus been established and characterized, which may be of use for chemo- and radiotherapeutic studies and for examining the mechanisms of cerebral oedema.