Teratogenic and embryo toxic effects induced by heavy metals in mice: the quest for a recent and more precise classification of fetal skeletal anomalies

Cadmium is a ubiquitous environmental contaminant and a potent teratogen in mice. For many experiments, hybrid mice obtained by crossing two inbred strains are preferable to either of the contributory pure lines because of theirs so called "hybrid vigor". The objective of this study was to compare the teratogenicity impact of cadmium in the NMRI and the hybrid mouse strain. A single dose of cadmium sulfate (3 mg/kg) was injected intraperitoneal into pregnant mice, early on the 9th gestation day. On day 19 of pregnancy, fetuses were removed from the uterus, weighed and examined for the frequency of resorption and the types and incidence of external malformations. The statistical analysis showed a significant fetal weight decreased in both strains, compared with control groups. Furthermore, there was marked differences between the two mouse strains, in fetal mortality and the types o f m a l fo r m a t io n s produced. Among the surv iv ing fetuses, exencephaly , c le f t pa la te and exophthalmia were the most common types of abnormalities. We also noted that both strains had higher skeletal abnormalities frequencies than control groups. It has been shown that in both strains, the skeleton is a system which is very sensitive to the teratogenic effects of cadmium. Also, the malformations frequency differed between the two strains. The results indicated that the effects of cadmium may be influenced by the mouse strains characteristics.