Teratogenic effects of lead in the mouse

Female mice of the C57B1 strain were mated and given from the first day of the pregnancy a normal diet, containing 1.1% of calcium, or a calcium-deficient one, containing 0.2% of calcium. Animals of the 2 groups were injected intra-peritoneally with 15 or 35 mg of lead acetate/kg at different times of the fetal organogenesis (8th, 9th, 10th or 12th day of the pregnancy). In the normal diet group, injection of lead increases the postimplantation mortality and the rate of skeletal anomalies among the fetuses. The anomalies are restricted to the anterior part of the axial skeleton and consist essentially in the fusion of 2 or more cervical vertebrae. In addition, lead diminishes the blood calcium levels in the pregnant females. In the calcium deficient group, all these effects of lead are considerably increased and fetuses suffer a loss of weight and delayed ossification. In the animals given such a diet but non lead-injected, the fetal weight is already diminished. However, the ossification and the rate of skeletal anomalies are not affected, and the blood calcium levels of the mothers are similar to those of the control females given a normal diet.