Fig. 1. Posterior transformation of the AFB in Hesx1^-/- mutants at early somite stages. (A,B) Dorsal view of the Pax2 expression domain in wild type (A) and Hesx1^-/- mutant (B) at presomitic stages. No significant differences are observable. (C) Dorsal view of the Pax6 expression domain in wild type (left) and Hesx1^-/- mutant (right) at the 0- to 1-somite stage. Note the reduction in Pax6 expression in the anterior NP (arrowheads). (D-G) Dorsal (D,E) and frontal (F,G) views of Pax3 expression domain in wild type (D,F) and Hesx1^-/- mutant (E,G) at the 2- to 3-somite stage. Pax3 expression domain is anteriorised in the Hesx1^-/- mutant (E,G). Arrowheads indicate the rostral limit of Pax3 expression. (H-K) Dorsal (H,I) and frontal (J,K) views of Foxd3 expression domain in wild type (H,J) and Hesx1^-/- mutant (I,K) at the 2- to 3-somite stage. Foxd3 expression domain is anteriorised in the Hesx1^-/- mutant (I,K). Arrowheads indicate the rostral limit of Foxd3 expression. Anterior is to the top in A-E,H,I.