Embryotoxicity of 1,2-dibromoethane in chick embryos in ovo: Early and late effects

Embryotoxic effects of 1,2-dibromoethane (DBE), a compound still widely use d in industry, have been analyzed using chick embryos in ovo. Administratio n on embryonic days (ED) 3, 4 or 5 induced dose-dependent embryotoxicity, m anifested namely as the early embryonic death. A serious disturbance of the vascular system represented probably the main cause of strong embryolethal ity and growth retardation in the group of survivors. Amniotic bands in the parietal region and defects of brain and aorta prevailed In the malformati on spectrum registered on ED 10. The local character of early induced chang es suggests a direct effect of DBE itself in the embryotoxic action. This p rocess is probably accomplished through interaction with lipids in cell mem branes owing to the hydrophobic character of DBE molecules. The results, ho wever, did not exclude an involvement of reactive metabolites in final embr yotoxicity via the formation of DNA-adducts. In any case, a decreasing embr yotoxicity of DBE with the age of treated embryos documented that the onset of liver function, assumed to occur on ED 5, did not increase the efficacy of DBE bioactivation. Our results confirmed the short-term embryotoxic pro perties of DBE reported in rat embryonic cultures. In addition, the in ovo system enabled us to reveal also long-term consequences represented namely by the formation of amniotic bands, not detectable in studies in vitro. The results obtained with the chick embryo in ovo confirmed the suitability of this system for embryotoxicity testing.