Fig. 5

Class 3 secreted semas are expressed in the cranial NC-free zones. In A–U, sema expression is in blue, and engrailed3, krox20, and dlx2 are in pink or orange. In V–Y, krox20 and dlx2 are in blue. Arrows indicate the second cranial NC stream. (A–B) sema3Aa is expressed in the head periphery between the second and third cranial NC streams (arrowhead), and its expression appears unaffected in lzr/pbx4 mutants. (C–D) sema3Ab is not expressed in the head periphery of wild-type embryos, but its expression is expanded in the head periphery between the second and third cranial NC streams of lzr/pbx4 mutants (arrowhead). (E–F) sema3C is expressed in the OV (arrowhead) in wild-type embryos, and its expression is also unaffected in lzr/pbx4 mutants (G–H) sema3D is expressed in the second cranial NC stream (arrow) in wild-type embryos, but the expression is gone in lzr/pbx4 mutants. sema3Fa (I–J), sema3Ga (M–N), and vegf₁₆₅ (Q–S) are expressed in the cranial NC-free zones (asterisks) in wild-type embryos and their expression is expanded in the head periphery of the lzr/pbx4 mutants (arrowhead). (K–L) sema3Fb is not expressed in the head periphery. (O–P) sema3Gb is expressed in cells surrounding the cranial NCCs in the wild-type embryo (white arrows) and its expression is expanded in the head periphery of lzr/pbx4 mutants (arrowhead). (T–U) The expression of sema3Fa (T) and sema3Ga (U) in the endoderm (arrows) and/or mesoderm (arrowheads) of the cranial NC-free zones in wild-type embryos is examined in cross sections, whose positions are indicated as red asterisks in I and M. (V–Y) MO knockdown of Sema3Fa (V), Sema3Ga (W), Sema3Gb (X), or Sema3Fa/3Ga (Y) in lzr/pbx4 mutants partially suppresses the cranial neural crest fusion phenotype, resulting in the re-appearance of a cranial NC-free zone (asterisks) in V–Y. Scale bar: 40 μm in A–S and V–Y; 20 μm in T–U.