Fig. 5. In situ hybridization showing expression of differentiation and patterning markers in normal (+/+ or +/–) and Tbx3^tm1Pa homozygous mutant (–/–) embryos. (A) Fgf8 expression in 10.5 dpc wild-type and homozygous mutant embryos showing the thinner and anteroposteriorly less extensive AER. (B) Tbx2 expression is absent from the posterior margins of the mutant limbs (arrows indicate posterior margins) but is present at the anterior margin at 11.5 dpc. (C,D) Tbx4 and Tbx5 expression in the hind- and forelimbs, respectively, is normal in mutant embryos at 11.5 and 10.5 dpc, respectively. (E,F) Shh expression at 10.5 and 11.5 dpc, respectively. Expression is absent or reduced in homozygous mutants compared with wild-type controls. (G) Hand2 (dHand) expression is reduced in the forelimb and absent from the hindlimb of mutant embryos at 10.5 dpc.