A group of 5 selected malignant meningiomas was studied in relation to the incidence and morphology of the mitoses. Beside a high mitotic rate many structural chromosomal abnormalities were observed. In agreement with other malignant onco-types previously studied, the authors suggest that atypical mitoses together with a tissue and cytological undifferentiation may be assumed to be an important prognostic criterium for meningiomas. The problem of malignancy in meningiomas has not been, so far, satisfactorily resolved, so that, in our opinion, the definition of even minimal details may be of some interest. For example, as it clearly appears from reviewing the literature on this sugject, no particular attention has been paid to the mitotic features. Referring to previous studies on the mitotic abnormalities in different malignant cerebral onco-types, the authors aimed to examine the various mitotic aspects in a limited group of tumors selected on the basis of clinical and histological malignancy.
The distribution of acid phosphatase and non-specific esterase in glia cells of normal and pathological human nervous tissue has been histochemieally studied.Acid phosphatase is prominent in cortical glia, especially in the first layer astrocytes, while non-specific esterase prevails in white matter oligodendroeytes. In reactive glia both enzyme activities result increased. The iatracellular sites of enzyme activity correspond to PAS-positive and autofluorescent material which represents largely lipopigments. The two enzyme activities studied seem to be associated to these structures. The use of inhibitors and activators allows to recognize that non-specific esterase partly is sensitive and partly is resistant to E 600. The former prevails ia white matter oligodendroeytes and the latter is prominent in pericytes and reactive glia cells, pCMB failed to give histoehemically any enzyme modification.The significance of the findings in the different glia forms is discussed.
✓ Tumors of the nervous system grew in rats treated at birth with ethylnitrosourea through intracerebral or subcutaneous routes and in fetal rats treated through the mother. In 80% to 85% of the rats, single and multiple tumors developed in the brain and spinal cord regardless of the route of administration. Gasserian neurinomas, oligodendrogliomas, and oligogendroglial foci were the most frequent neoplasms. General morphological aspects and frequency of tumor localizations in relation to drug administration route are discussed. Thymidine incorporation into DNA, and RNA/DNA ratio, were evaluated in order to estimate tumor proliferation rate and growth. Desmosterol, a characteristic sterol of brain tumors, was detected in all the tumors. Regions of the brain and spinal cord of treated rats showed the presence of microscopic pretumoral areas (oligodendroglial foci) which incorporated thymidine into DNA in contrast to the brains of control rats.
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