Fig. 1. Ets2 expression profile and morphological classification of Ets2^db1/Ets2^db1 conceptuses. (A-E) Ets2 expression from pre-implantation (E3.5) to early head-fold stage (E7.75). Note that Ets2 is not expressed in the polar trophectoderm prior to implantation, but its expression is trophoblast specific from E5.0-E6.75, and by the early head-fold stage it is also expressed in the PS (asterisk in E). (F-H) Conceptuses on the left of each image are whole-mount views; those on the right are sagittal semithin sections of the same type of embryo. Type-I (H) and type-II (G) Ets2 homozygous mutants tend to be smaller than their wild-type (F) littermates. Type I mutants also have a short PPT, as judged by the position of the embryonic-extraembryonic junction (small arrows), and an abnormally thickened anterior-distal VE (dashed lines), and show absence of mesenchymal (m) cells. Whole-mount images in A-D, and in F-H are of the same magnification. Sections in F-H are of the same magnification with the exception that the right image in H is an enlargement of the image to its left. Scale bars: 100 µm.