The effects of lanthanum chloride on pregnancy in mice and on preimplantation mouse embryos in vitro

Abstract

A single intraperitoneal injection of 10 −6.5 mol lanthanum chloride/g body wt (44 mg metal/kg body wt) into pregnant mice reduced the number of successful pregnancies and the average litter size. The most susceptible periods of pregnancy were peri-implantation (days 4 and 6) and near-term period (days 14 and 16). Injection of lanthanum during the peri-implantation period resulted in a cessation of pregnancy in 24–43% of females, and injection during near-term period produced the cessation of pregnancy in 36–46% of the females. The average litter size after injection of lanthanum during peri-implantation or near-term periods was reduced to about 75% of the average litter size in the control animals. No external malformations were observed among fetuses. Paradoxically, the exposure of 1-cell stage embryos to 10 −3.0 M and 10 −3.5 M lanthanum chloride in vitro resulted in a significant improvement of the proportion of embryos developing into blastocysts.