Experimental induction of primitive neuro-ectodermal tumours 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 with histological, immunohistochemical and ultrastructural techniques. Although with conventional histological techniques, most of the induced tumours showed morphological features suggesting their classification as malignant schwannomas or oligodendroglioma-like neoplasms, their study by means of immunohistochemistry and electron microscopy suggested that they are, in fact, primitive neuroectodermal tumours, with a tendency toward neuronal differentiation. This finding obliges us to re-appraise the ethyl-nitrosourea model of neurocarcinogenesis and to consider its possible usefulness for the experimental study of therapeutic approaches with potential applications in human neuro-ectodermal neoplasms.