Fig. 2. Hh signaling and limb prepattern is defective in Ift88^hypo mutant limbs. (A,B) E10.5 forelimbs. (A) Shh is expressed in the posterior mesenchyme in wild-type limbs at E10.5. (B) Shh expression is normal in Ift88^hypo limbs. (C) Ptch1-lacZ is strongly expressed in cells adjacent to the Shh expression domain in wild-type E11.5 limbs. (D) Ptch1-lacZ (Goodrich et al., 1997) is expressed at very low levels in Ift88^hypo E11.5 limbs. (E,F) E10.5 hind limbs. (E) Gli1 is expressed in the posterior region of the wild-type limb bud at E10.5. (F) Gli1 expression is downregulated in Ift88^hypo limbs at E10.5; (G,I) Hand2 (dHand in figure) is expressed in the posterior region of the wild-type limb bud at E10.25 and E10.5, respectively; (H,J) Hand2 expression is upregulated and anteriorly expanded in Ift88^hypo limbs at both E10.25 and E10.5. (K,M) Gli3 RNA is expressed throughout the wild-type limb bud, except in the most posterior domain at E10.25 and E10.5. (L,N) In Ift88^hypo limbs at E10.25, Gli3 is expressed as in wild type, but later expands into the posterior mesenchyme. Green arrows indicate gene expression in normal limbs; red arrows indicate gene expression in Ift88^hypo limbs; brackets indicate gene expression in Ift88^hypo limbs.