Early stage of development of transplacentally induced glioma with ethylnitrosourea in rats. Sequential historadioautographic and electron microscopic studies.
Proliferative activity of possible preneoplastic cells (subependymal cells and glioblasts), early neoplastic cells and glioma cells induced by transplacental ethylnitrosourea (ENU) treatment in the rat was analysed by historadioautography and electron microscopy. Labeling index of 3H-thymidine in subependymal cells was the highest in the cerebrum of postnatal age, but no difference was observed between the normal and ENU treated groups. Thus, preneoplastic cells could not be distinguished from normal cells by morphology and proliferative activity. Focus of early neoplastic proliferation was composed of rather heterogenous and less differentiated cells, such as oligodendroblast-, glioblast- and subependymal cell-like cells, and preferentially located around the periventricular areas. Labeling index of early neoplastic proliferation was very low although the value gradually increased with age. Proliferative activity of glioma cells was higher than that of the early neoplastic cells and lower than subependymal cells, and further differed according to the degree of differentiation and morphological type. Finally, it is suggested that glioma might develop mainly through the differentiation from the focus of early neoplastic proliferation.
D000818:Animals; D001345:Autoradiography; D001932:Brain Neoplasms / Q000139:chemically induced / Q000473:pathology* / Q000648:ultrastructure; D002455:Cell Division; D005038:Ethylnitrosourea; D005260:Female; D005315:Fetal Diseases / Q000139:chemically induced; D005910:Glioma / Q000139:chemically induced / Q000473:pathology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains
D005038:Ethylnitrosourea