Effect of cadmium exposure during porcine embryonic development. (A) Bright-field images of embryos on days 2 and 6. Bar = 200 µm. (B) Cleavage rate and (C) blastocyst formation rate (0; n = 132, 20; n = 133, 40; n = 133, 60; n = 133). (D) Representative images of blastocysts at the early blastocyst (EB), middle blastocyst (MB), large blastocyst (LB), and expanded blastocyst (ExB) stages. Bar = 50 µm. (E) Proportion of various blastocyst stages (0; n = 47, 20; n = 50, 40; n = 24). Values with different superscript letters (a, b, and c) differ significantly (p < 0.05). Data are compiled from four independent experiments.