Effect of LiCl on differentiation of mouse embryos beyond the blastocyst stage

In order to test the effect of Li+ on cell differentiation, 2-cell embryos were cultured in vitro with or without Li+ to the blastocyst stage and then, in a "implantation" culture medium, with or without Li+, up the early egg-cylinder stage. Our results show: 1) that Li+ in the preimplantation medium diminishes "implantation" success significantly; 2) that trophoblastic vesicles, produced by culturing preimplantation embryos with Li+, do not generate an inner cell mass when further cultured in "implantation" medium; 3) that the ultrastructure of "implanted" embryos is similar in all experimental series.