Fig. 1. Schematic representation of the formation and fate of the first cell lineages of the mouse embryo.
The pluripotent epiblast (red) will form the embryo proper. The trophectoderm (green) will give rise to the fetal portion of the placenta and contribute to the yolk sac. The primitive endoderm (blue) will differentiate into the parietal and visceral endoderm that will constitute the yolk sac. The visceral endoderm will also be incorporated into the embryonic endoderm (blue dashed line). EPI, epiblast; ExE, extraembryonic ectoderm; PE, parietal endoderm; PrE, primitive endoderm; TE, trophectoderm; VE, visceral endoderm.