Morphological Study of Central Nervous System Malformations Induced by Ethylnitrosourea in Rats

Abstract

In order to evaluate the teratogenic effects of ethylnitrosourea (ENU), a transplacental carcinogen, on the developing central nervous system of the rat embryo. ENU was administered intravenously to pregnant rats on day 9, 12, 14 or 18 of gestation. All malformations induced were specific for the developmental stages. Hydrocephalia was divided into two groups, obstructive and dysgenetic, in relation to developmental mechanism. Micrencephalia associated with hypoplasia of the telencephalon and disorderly arrangement of the lamellar structure in the pallium was produced by treatments on day 12 and day 14. Irregular migration of neuronal cells and cell death caused by the cytotoxic effect are considered to be the developmental mechanisms of micrencephalia. Meningocele, meningoencephalocele, anencephalia and acrania might be a series of malformations which developmental mechanisms were related each other. The relationship of anencephalia or acrania to the development of micro-holoprosencephalia is suggested. Distinctive and common features of these malformations were hypoplastic deformities of the telencephalon .