Fig. 6. The FEZ graft induces an ectopic outgrowth in the mandible. (A) Lateral, (B) ventral and (C) frontal views of chimeric embryos with ectopic outgrowths (red arrow) that formed 7 days after transplantation. No ectodermal appendages, such as the egg tooth (et), were present on the outgrowths. (D,E) Meckel's cartilage (mk) was bifurcated (arrow) in the ectopic outgrowth and was surrounded by ectopic bone that was continuous with the dentary bone (db). Broken line demarcates the bifurcation of Meckel's cartilage. The end of the ectopic element (arrowhead) resembled the mandibular symphysis. (F) Sagittal section through the head of chimeric embryo 24 hours after transplantation demonstrates that in the mandible, Shh (yellow) and Fgf8 (green) are normally expressed in adjacent domains in the oral ectoderm (arrows). By 24 hours after transplantation, Shh (yellow) and Fgf8 (green) transcripts were still detected in the FEZ (asterisks), which was grafted to the aboral side of the mandible. Fnp, FNP; mx, maxillary process; fg, foregut. Scale bars: 2 mm in A-C; 1 mm in D,E; 0.5 mm in F.

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