Differential cadmium-induced embryotoxicity in two inbred mouse strains 1. Analysis of inheritance of the response to cadmium and of the presence of cadmium in fetal and placental tissues

NAW-wa-2 + /Pr (NAW) mouse embryos and fetuses were relatively resistant to death caused by maternal injection of Cd on days 81–17 of gestation, and C57BL/10ChPr (B10) mouse embryos and fetuses were relatively susceptible, Crosses indicated that sensitivity to Cd-induced embryotoxicity was inherited by a complex pattern with a possible maternal effect. Studies using maternal injections of 109Cd at 10 days' gestation indicated that Cd crossed the placenta in both the sensitive and resistant strains since 109Cd was detected in embryos and placentas at 1–24 h postinjection. Fractionation of the tissue cytosol preparations by Sephadex gel G-200 filtration indicated that free Cd was absent from embryos and placentas of both strains. In embryonic cytosol of both strains 109Cd was associated with fractions showing elution characteristics indicative of Cd-binding protein (metallothionein, MW 10,000). In placental cytosol of both strains 109Cd was predominantly associated with fractions whose characteristics indicated a moiety of approximately 19,000 MW. The two strains differed only in the amount of Cd present in the embryonic cytosol — B10 embryos had more Cd in the binding-protein fractions than did NAW embryos. To evaluate the placental capacity for transfering Cd throughout gestation females were injected on day 13 and 17 of gestation; l09Cd was detected in embryos, fetuses, and placentas of both strains 4 and 24 h postinjection, In contrast with day-10 results gel profiles from offspring and placentas were qualitatively similar, i.e., the heavier (dimeric?) Cd-binding molecule was not present in placental cytosol. B10 embryonic mortality was greater at these later gestational times.