Figure 5. Shh signaling appears expanded in schlei mutant limbs at e11.5.
Despite a normal domain of Shh (A,B), the boundary (arrowhead) of expression of Gli1, a direct target of Shh, is expanded anteriorly in schlei mutants (C,D). Note also the increased width of the mutant limb relative to the control, an early indication of polydactyly (visible in B,D). Expression of Ptch1 appears unchanged in the mutant, suggesting differential sensitivities of various Shh targets (E,F). Gremlin, a downstream target of Shh activation, is expressed ectopically in a distinct region (arrow) in the anterior of the schlei limb (G,H). Control and schlei mutant images are shown at the same magnification.
