In VitroComparative Effect of Cd2+, Ni2+, and Co2+on Mouse Postblastocyst Development

Postblastocyst development of mouse preembryos was studiedin vitroin order to determine direct effect of Cd2+, Ni2+, and Co2+ions on embryogenesis during the peri-implantaion stage. Uterine horns were flushed on Day 4 of pregnancy and expanded blastocysts were cultured for 4 days in the presence of micromolar Cd2+(1.1–26.4), Ni2+(0.1–500) or Co2+(1–200). Area of trophoblast outgrowth was measured and used as a quantitative toxicological endpoint. Hatching, attachment, outgrowth, and formation of inner cells mass were also registered. Significant adverse effect on the development stages were observed at 2.2 μM (Cd2+), at 10 μM (Ni2+), and at 100 μM (Co2+). Cd2+and Co2+decreased the area of trophoblast markedly at concentrations of 1.1 and 10μM, respectively. Ni2+exposure resulted in a slight increase at 10 μM followed by a marked reduction in the trophoblast area at 250 μM. Reduced proliferative ability of trophoblast cells may point to compromised invasiveness of the embryo. The lowest Cd2+concentration (1.1 μM=0.25 μg/ml) significantly deteriorating trophoblast development was found to be lower than Cd levels ranging up to 0.512 μg/g, reported in clinical ovarian samples of occupationally nonexposed women. The morphological alteration and loss of cellular contacts in blastocysts induced by exposure to Cd2+, Ni2+, or Co2+may adversely influence adhesion and recognition events and may disturb aggregation of mononuclear trophoblastic cells to multinucleated cells in the course of peri-implantationin vivoas well.