Influence of short-term maternal zinc deficiency on the in vitro development of preimplantation mouse embryos.

In this study, we evaluated the use of mouse preimplantation embryos as a model to study zinc deficiency-induced abnormal development. In Experiment 1, the effect of culture medium Zn concentrations on blastocyst development was studied. Preimplantation embryos (2 and 4 cells) obtained from superovulated females developed normally in media containing 0.7-30 microM Zn for up to 72 hr; higher levels of medium Zn resulted in abnormal development. In Experiment 2A, females were fed diets containing 50 (+Zn) or 0.4 (-Zn) micrograms Zn/g (760 vs 6 nmol/g, respectively) from 1 day before to 1 day after mating (3 days total). Preimplantation embryos were removed from the dams and cultured for 72 hr in 0.7 microM Zn medium. Embryos from the -Zn dams were morphologically normal at time zero; however, over the 72-hr period, these embryos tended to develop at a slower rate than controls, although compaction and cavitation frequency were similar. By the end of the 72-hr culture period, embryos from -Zn dams had significantly fewer cells than did embryos from control dams. In Experiment 2B, an extended period of maternal Zn deprivation (6 days) was used to investigate the potential for further impairment of in vitro preimplantation embryo development observed in Experiment 2A. Results from this experiment were consistent with those from Experiment 2A, in addition to providing evidence that the developmental progress of embryos obtained from mice fed Zn-deficient diets for 6 days was significantly impaired. In Experiment 3, the potential for supplemental Zn in culture medium to overcome the impairment in development due to maternal Zn deficiency was investigated. Embryos from female mice subjected to the same dietary regimen described in Experiment 2A were cultured to the blastocyst stage in medium containing Zn at a concentration of either 0.7 or 7.7 microM. Medium Zn supplementation did not improve development of embryos from dams fed Zn-deficient diets. In summary, embryos from mice fed -Zn diets for a 3- or 6-day period encompassing oocyte maturation and fertilization exhibited impaired development in vitro. This impairment was not overcome by medium Zn supplementation.