Additional file 7. Homozygous lethality of Setdb1gt/gt embryos. Representative bright field images of E7.5 Setdb1 +/+, Setdb1 gt/+, and Setdb1 gt/gt embryos at 63 × magnification. Embryonic (em), extra-embryonic (ex) and ectoplacental cone (ec) tissues are indicated. Scale bar represents 200 µm.