Variability in the embryotoxicity and fetotoxicity of vanadate with the day of exposure.

The aim of this study was to assess the variability in the developmental toxicity of vanadate with the day of administration during gestation. Single ip injections of 25 mg sodium metavanadata/kg were given to albino Swiss mice on one of the days 9-12 of gestation. Dams were killed on day 18 of pregnancy, and fetuses were examined for external, internal and skeletal malformations and variations. The number of dead or resorbed fetuses/litter, as well as the percentage of postimplantation loss, were significantly increased with injections on days 9-12 of gestation. However, the most sensitive time for the induction of metavanadate embryotoxicity was gestational day 12. Metavanadate treatment on day 12, but not days 9-11, resulted in a significant decrease in the fetal body weight/litter. There were no external, internal or skeletal malformations, whereas the most common skeletal variations were a reduced ossification in the parietal bone, metatarsals and metacarpals, bipartite sternebrae and fused ribs. The highest percentage of total skeletal defects was found on day 12 (82.3%). Gestational day 12 is the most sensitive time for metavanadate-induced developmental toxicity in mice.