EXPERIMENTAL INDUCTION OF PRIMITIVE NEURO-ECTODERMAL TUMORS IN RATS -A RE-APPRAISEMENT OF THE ENU-MODEL OF NEUROCARCINOGENESIS

A series of 122 experimental brain tumours, induced in the Wistar rat by means of prenatal exposition to ethyl-nitrosourea, were studied wit h histological, immunohistochemical and ultrastructural techniques. Al though with conventional histological techniques, most of the induced tumours showed morphological features suggesting their classification as malignant schwannomas or oligodendroglioma-like neoplasms, their st udy by means of immunohistochemistry and electron microscopy suggested that they are, in fact, primitive neuroectodermal tumours, with a ten dency toward neuronal differentiation. This finding obliges us to re-a ppraise the ethyl-nitrosourea model of neurocarcinogenesis and to cons ider its possible usefulness for the experimental study of therapeutic approaches with potential applications in human neuro-ectodermal neop lasms.