Oct 1, 2000
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Journal
Brain Pathology
Abstract
Ethylnitrosourea (ENU) is a transplacental carcinogen that is used experimentally to induce gliomas in the brain of laboratory animals. Brain tumors induced by ENU have been used to study the effects of potential therapeutic agents and of various possible promoting agents. Recently, ENU has been used to initiate brain tumors in rats for detection of the possible promoting effects of electromagnetic energies, including cellular telephone radiofrequencies. In two such studies, peer review of brain lesions by experienced pathologists disclosed a troublesome variation in tumor diagnosis. Since some histotypes are known to be more malignant than others, a failure to consistently classify these tumors may adversely impact research using this model. This study was undertaken to clarify the morphologic criterion for classification based on thorough histologic study of over 300 murine gliomas and by comparison with human brain tumors. With the aid of immunohistochemistry, it was possible to define the cellular features and patterns of typical and anaplastic rat astrocytomas, oligodendrogliomas and mixed gliomas and to distinguish them with proficiency. It was concluded that the classification of rat ENU gliomas should be based on thorough morphologic and immunohistochemical characterization such as provided by this study.