[Experimental brain tumors produced transplacentally by ethylnitrosourea (IV): ultrastructure studied by using transmission and scanning electron microscope (author's transl)].

The fine structure of rat gliomas induced transplacentally with a single i.p. dose of 50 mg/kg of Ethylnitrosourea has been studied by using transmission and scanning electron microscope. The subependymal matrix layers of the fetus which was affected by ENU have showed irregular and rough arrangements with expanded extracellular spaces as compared with that of control rats. The cells of subependymal layer seemed to form the microtumor. A so-called "microtumor", which was found in a 8 week old, has been composed of small round cells. The fine structures of these cells have showed the characteristics in primitive oligodendroglioma. The characteristics of the fine structure of astrocytoma cells was identified by both TEM and SEM. The fine structure of subependymal glioma cells was often pleomorphic. These gliomas contained a mixture of primitive oligodendrocytes and ependymal cells together with anaplastic glial cells. With increasing size, the glioma has become more pleomorphic with a mixture of neoplastic oligodendrocytes, astrocytes and ependymal cells, and ependymoma like cells have showed neither cilia nor junctional complex. Abnormal vascular structure in the tumor has been reconfirmed by injection replica scanning electron microscope method. The fine structure of the separated single tumor cell surface was also studied by scanning electron microscope. The differences of the cells surface between that of astrocytoma cell and oligodendroglioma cells were clearly noticed.