Fig. 5. Two other types of labeled cell distribution after injection at the four-cell stage. (A-D) In the second type of distribution, only extra-embryonic ectoderm contained X-gal-positive cells. (A,C) Whole mounts; (B,D) sections of the embryos in A and C, respectively. In both embryos, a portion of trophoblast giant cells (arrows) and a part of the ectoplacental cone is for X-gal-positive. Note that embryo 4-59 (C,D, arrows) has labeled cells localized to the trophoblast giant cell layer. (E,F) The last type of cell distribution. In this embryo, there were no X-gal-positive cells in the extra-embryonic ectoderm region. In other regions, X-gal-positive and -negative cells were intermingled. Scale bars: 300 µm (A), 150 µm (B).