Cadmium uptake and distribution in mouse embryos following maternal exposure during the organogenic period: a scintillation and autoradiographic study

Pregnant C57BL/6J mice were given a single intraperitoneal injection of either a teratogenic (2,400 micrograms Cd/kg) an intermediate (40 micrograms Cd/kg) or a trace dose (0.66 micrograms Cd/kg) of cadmium chloride (CdCl2) on day 9 of gestation; each dose contained 109CdCl2 (20 microCi). The mice were euthanized at various times after Cd exposure, and the amount of Cd in the embryos was determined in a gamma counter. For all three doses a low, but similar, percentage of the dose rapidly entered the embryos; levels then decreased during the next 11 hours, only to rise again by 24 hours and continue to rise for the remainder of the pregnancy. When the Cd content was related to embryonic weight the Cd concentration was at its highest level after 1 hour and then decreased rapidly and continued to decrease for the rest of pregnancy. Autoradiographic studies showed that the teratogenic dose of Cd entered all tissues of the embryos but was particularly localized in cells of the neural tube, limb buds, and gut. By 12 hours, cell damage was seen in the embryos but the affected cells were not necessarily the heavily labelled cells. In embryos exposed to the nonteratogenic dose the highest Cd accumulation was seen in the embryonic gut and limb bud ectoderm but all tissues showed a low level of labelling.