Fig. 6. Effect of the ectopic Hoxb4 expression on head morphogenesis. At E6, when compared with quail-grafted-control embryos (A), which exhibit a normal face, the embryos that develop with Hoxb4-expressing diencephalic crest cells (D) have no nasal bud and a reduced first branchial arch. (B,C) At E8, untransfected neural crest cells grafted in control embryos ensure the normal development of the facial and mandibular skeleton. (E,F) In embryos carrying Hoxb4-transfected neural folds, the sella turcica is the most rostral skeletal structure, as the upper beak skeleton is missing. In the first branchial arch, the skeleton is reduced to its proximal elements: quadrate, articular and the proximal region of Meckel’s cartilage. St, sella turcica.

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