Fig. 7. Shhcre;Fgfr1 digit condensation and Shh-expressing cell lineage. In all panels, anterior is towards the left and posterior towards the right. (A-D) Digit condensations outlined by Sox9 expression. Dots in A and B indicate individual digit condensations that are beginning to separate. All curved lines in C and D are the same length. All lines are the same length. The lines in C span the entire distance between each pair of condensations, while the line in D does not, indicating that the middle two condensations in D are farther apart than normal. Pattern in C indicates that each condensation has its unique morphology. In particular, digit 2 and 4 condensations have a slight curve towards the straight digit 3 condensation at the midline of the AP axis. In D, the middle two condensations exhibit a curve towards the AP midline, resembling digit 2 and 4 condensations in a normal limb bud. (E-H) ß-Gal staining to label Shh-expressing cell lineage in normal (Shh^cre/+;Fgfr1^co/+;R26R/+) and Shhcre;Fgfr1 (Shh^cre/+;Fgfr1^co/co;R26R/+) forelimb buds. Dots in E and F indicate the position of condensations as deduced from Sox9 expression in an equivalent staged limb bud. Broken lines in E-H indicate anterior boundary of the Shh-expressing lineage.