Figure 4.

Shp2 mutant cells show reduced contribution to the mesodermal wings of gastrulating chimeric embryos. wt (A, C, and E) and Shp2 mutant (B, D, and F) chimeras in whole-mount (A and B) or tissue sections (C–F). Anterior is to the left. ES cells do not contribute to the extraembryonic region and primitive endoderm of chimeric embryos and are therefore unstained. Arrow in D points to hyperaccumulation at the posterior epiblast (leading to a misshapen epiblast at this region fated to become neuroectoderm); similarly, arrowhead in F points to buildup of mutant cells within the posterior epiblast. end, endoderm; me, mesoderm; epi, epiblast; ng, neural groove; ext, extraembryonic region; ps, primitive streak.