Fig. 4.

Expression domains of T-box genes during mouse pre-implantation and early post-implantation embryo development. Tbx3 is expressed in the inner cell mass of the pre-implantation embryo and later in the extraembryonic endoderm of the developing yolk sac. Mga is also expressed in the inner cell mass at pre-implantation stages and then in the epiblast of the post-implantation embryo. Eomes is expressed in the trophectoderm layer of the blastocyst and after implantation is expressed in the extraembryonic ectoderm and later the chorion, the visceral endoderm, including the anterior visceral endoderm, and the posterior proximal epiblast. T is expressed in the posterior epiblast and extraembryonic ectoderm and later in the core of the allantois, the primitive streak and node. Tbx6 overlaps T in the primitive streak but is not expressed in the node. Tbx4 is expressed in the allantois. AVE, anterior visceral endoderm; EPC, ectoplacental cone; ExE, extraembryonic ectoderm; ExEn, extraembryonic endoderm; ICM, inner cell mass; TE, trophectoderm; VE, visceral endoderm.