Fig. 2

Fate mapping by homotopic transplantation. Fate mapping by single-cell injection indicated that hindbrain progenitors are located at a sector 40–90° from the midline of a shield-stage gastrula. (First panel) Labeled grafts taken from this region and placed into the same position in an unlabeled host gave rise to cells that spanned the entire hindbrain region, as predicted by the fate map. (Second panel) A labeled graft made to the ventral most sector of the ectoderm gave rise to cells in the posterior trunk and tail, which include ectodermal cells, endoderm, and somitic cells. (Third panel) To map the position of hindbrain progenitors at 80% epiboly, labeled cells were orthotopically replaced into the shield-stage embryos, and the location of labeled cells was tracked at 80% epiboly. The majority of the hindbrain progenitors fate map to the middle third of the epiblast, adjacent to the dorsal axis.