[Morphology and classification of brain tumors induced by methylnitrosourea in rabbits (author's transl)].

There are different opinions concerning histology and classification of the MNU induced rabbit brain tumors first described by Jänisch and Schreiber. Therefore, a reexamination using silver impregnation of paraffin sections gained from the blocs was made. 40 out of 53 tumors were classified according to their prevalent cell types as glioblastomas, astroblastomas and malignant astrocytomas. Their structure is complicated by an admixture of various amounts of oligodendroglia, microglia and glioepithelium (mixed gliomas) and in most of them a raise of malignancy up to the appearance of glioblastoma multiforme in their central parts. The rest group contains 3 oligodendrogliomas, 4 sarcomas, 1 gioepithelioma and 5 times areas of loose tumor cell infiltrations. These results do not confirm the opinion of Zülch that the majority of MNU rabbit brain tumours are polymorphous oligodendrogliomas but are in accordance with their classification as polymorphous glioblastomas by Jänisch and Schreiber.