[Histogenesis of neurinomas induced in rats by nitrosoethylurea]

Twenty-five tumors of the peripheral nerves induced in BD rats by N-nitrosoethylurea were studied by peroxidase-antiperoxidase method using specific anti-serum against protein S-100. Eighteen tumors gave positive reactions for S-100 protein, including those with invasive growth. Protein S-100 was always present in cystic neurinomas. No protein was found in seven tumors. It is concluded that most tumors studied originated from Schwann cells, while at least some of them had a connection with the peri(endo)neurium.