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Summary Malignant neurinomas can be induced in BD IX rats by transplacental application of ethylnitroso-urea during pregnancy. Tumors develop in the offspring in trigeminal and spinal nerves and can be easily transplanted upon rats of the same strain. During the first passages a considerable shortening of subsequent induction periods takes place. Concurrently, silver stained Nucleolar Organizer Regions (AgNORs) increase in number and other measured AgNOR parameters change in a similar way. The number of cells that express the proliferation marker PCNA equally becomes more frequent during the first subcutaneously transplanted generations. There is high correlation between AgNOR parameters, number of PCNA expressing cells, induction times and passage. It is concluded that the first generations of the transplantation model of these tumors can be used to test the validity of proliferation indicators. Our results show further that AgNORs in fact belong to the group of markers of proliferation.

Summary Contradictory results have been reported claiming either none, partial or almost complete correlation between the complexity of GSL compound profiles and the assumed glial tumor differentiation. Therefore an attempt was made to compare GSL patterns with both the general (final) tumor diagnosis and malignancy grade (WHO) as well as the regional evaluation of the histology and the grading in the tumor tissue pieces directly subjected to biochemical analysis. Regional and general (final) diagnosis did not always correspond, especially when more than one tissue sample of a given tumor was analyzed. Four GSL component patterns were identified by TLC: GSL-type I with gangliosides primarily of the simple G lac -family lacking sulfatide and the more complex G tri - and G tet -gangliosides, GSL-type II with ganglioside of the G lac - and G tri -families, also without sulfatide, and GSL-type III, with more complex gangliosides of the G tri and G tet -families in addition to G lac -gangliosides and sul fatide, similar to the normal brain pattern, and the pattern of normal brain. There was only insufficient correlation between these GSL-type patterns and final diagnoses. However, between regional diagnosis of astrocytoma II and GSL-type III on the one hand and glioblastoma multiforme IV and GSL-type I on the other hand, a coincidence of more than 85% was found. In only 50% the intermediate GSL-type II and glioma III were associated. There was no relation between GFAP or vimentin expression and histology or GSL-type both with regard to final and regional diagnoses. Regional astrocytoma architectures exhibiting GSL-type III were mostly fibrillary, whilst glioblastomas with GSL component pattern I had often a giant cell make up. In conclusion regional biochemistry must be compared with the corresponding regional histology and grading, disregarding the overall (general or final) diagnosis, which reflects the most essential or malignant tumor part. Then ganglioside component patterns can be correlated to malignancy grades. This allows the consideration of gangliosides as candidates for malignancy markers in human gliomas.

"Olfactory neuroblastoma" covers several types of esthesioneurogenic tumors such as esthesioneuroepithelioma, esthesioneuroblastoma and others. They are thought to be of olfactory mucosal origin and present with typical light microscopical "neurogenic features" e.g. rosettes and/or axon production. Some cases have been analyzed ultrastructurally and contained membrane bound granula like others tumors of the APUD system, originating from the neural crest. Furthermore neuronal differentiation of various degrees has been described. The human case of this contribution did not contain rosettes, but axons could be demonstrated in considerable number by silver impregnation. Electron microscopy could demonstrate the presence of dendritic processes with microtubuli and filaments as well as abundance of secretory granules of 1800 A. The comparison with the up to now published findings shows that the production of dense core granules is the most constant ultrastructural feature in these tumors; however, additional ultrastructural features in typical human cases as here presented, earlier experimental results and few human descriptions show, that DCV production is not essential for olfactory neuroblastoma. This might shed new light on the histogenesis of these tumors.