Fig. 4. Signalling molecules are correctly expressed in the second pharyngeal arch despite the loss of ncc. Wild-type (a,d,g,j), Hoxa1-/- (b,e,h,k) and Hoxa1-/-Hoxb1 3'RARE-/- (c,f,i,l) embryos were processed for whole-mount in situ hybridisation with Fgf3 (a-c), Fgf8 (d-f), Shh (g-i) and Bmp7 (j-l) antisense riboprobes. (a-c), Expression of Fgf3 in the first and second pharyngeal pouches (pp1 and pp2, respectively) was not changed in either Hoxa1-/- or Hoxa1–/-/Hoxb1 3'RARE-/- embryos (arrows). (d-f) The weak expression of Fgf8 on the second pharyngeal arch (pa2) was not abolished in either Hoxa1-/- or Hoxa1-/-/Hoxb1 3'RARE-/- embryos (arrows). (g-i) Expression of Shh in the second pharyngeal arch (pa2) was not abolished in either Hoxa1-/- or Hoxa1-/-/Hoxb1 3'RARE-/- embryos (arrows in). (j-l) Similarly, expression of Bmp7 in the second pharyngeal arch (pa2) was not abolished in either Hoxa1-/- or Hoxa1-/-/Hoxb1 3'RARE-/-embryos. ov, otic vesicle.
