Hox Genes Regulate the Definitive Forelimb Position
(A–C) Embryos electroporated with GFP in combination with Hoxb4+Hoxc9 dn in the interlimb domain at stage 14 and re-incubated for 48 hr. The unilateral expansion of the forelimb is denoted by red arrowheads compared to contralateral side denoted by green arrowhead (n = 13/22 embryos). (A’)–(C’) shows Fgf10 (A’), Tbx5 (B’), and Shh (C’) expression in corresponding embryos. White arrowhead in (A’) points at ectopic Fgf10 expression within the electroporated region.
(D–G) Embryos electroporated with GFP alone (D and F; n = 7 embryos) or in combination with Hoxb4+Hoxc9 dn (E and G; n = 22 embryos) in the interlimb domain at stage 14 and re-incubated for 4 days. (F and G) Alcian Blue staining in GFP (F; n = 5 embryos) or Hoxb4-Hoxc9 dn-GFP (G; n = 9 embryos) electroporated embryos is shown. Note the posterior shift of the forelimb on the right electroporated side of Hoxb4-Hoxc9 dn-GFP electroporated embryos (E and G; n = 11/22 embryos) highlighted with red dashed line (E) and red arrow (G). Stars, somites; dashed lines, forelimb outline; arrows, vertebral level of the forelimb.
Scale bars are 200 μm in (A)–(C) and (A’)–(C’) and 500 μm in (D)–(G). See also Figure S4.