Comparison between Evi1^KI/+ and Evi1^+/+ mice. (A) External morphology of Evi1^+/+ and Evi1^KI/+ mice. Images of 10-week-old male littermates. Gross appearance, face, left forelimb, and left hindlimb of Evi1^KI/+ mice compared with those of Evi1^+/+ mice. There are no external morphological abnormalities. (B) Representative embryos in their yolk sacs at E10.5. The Evi1^KI/KI embryo has an avascular yolk sac. Bars represent 2.4 mm. (C) Representative Evi1^+/+, Evi1^KI/+, and Evi1^KI/KI littermates at E10.5. The Evi1^KI/KI embryo has a flattened head and poor vascularization. Its size is almost the same as the size of Evi1^+/+ and Evi1^KI/+ mice. Bars represent 1.2 mm.