Fig. 3. Rostral expansion of dorsal diencephalic markers in Hesx1^-/- mutants at the 8- to 10-somite stage. (A-D) Frontal views of the Pax3 (A,B) and Foxd3 (C,D) expression domains in wild type (A,C) and Hesx1^-/- mutants (B,D). Both expression domains are anteriorised in the Hesx1^-/- mutants. Arrowheads indicate the rostral limit of Pax3 and Foxd3 expression. (E,F) Lateral view of the En1 expression domain in wild type (E) and Hesx1^-/- mutant (F). En1 expression domain around the midbrain-hindbrain region is normal in Hesx1^-/- mutants when compared with wild-type littermates. (G,H) Lateral view of the Pax2 expression domain in wild type (G) and Hesx1^-/- mutant (H). Pax2 expression around the midbrain-hindbrain boundary is normal (arrowheads), but there is no Pax2 expression in the AFB of the Hesx1^-/- mutant (arrow in G). (I,J) Lateral view of the Wnt1 expression domain in wild type (I) and Hesx1^-/- mutant (J). In the mutant, Wnt1 expression is expanded rostrally until the tip of the NP (arrowhead). (K,L) Dorsal view of the embryos depicted in I,J with anterior to the bottom. (M,N) Lateral view of the Wnt3a expression domain in wild type (M) and Hesx1^-/- mutant (N). Note the rostral expansion of Wnt3a expression in the prospective dorsal diencephalon (bracket). (O,P) Dorsal view of the embryos depicted in M and N with anterior to the bottom.