Fig. 2. Abnormal digit formation and limb development in Fgfr1^Co/Co;Ap-2Cre mice. (A) Forelimb of E11.5 Fgfr1^Co/Co;Ap-2Cre (Mt) and Fgfr1^Co/Cocontrol (Wt) mice. (B) Whole-mount in situ hybridization for Sox9 in E12 forelimbs. (C,D) Hoxd12 stained E13.5 forelimbs (C) and hindlimbs (D). The Hoxd12-negative digit is the first digit (1). Arrowheads in C indicate fused digits. (E-I) Alizarin Red and Alcian Blue stained newborn forelimbs (E-G), and P10 hindlimbs (H,I). The arrows in F-H indicate fused digits. The boxed area in E is enlarged in F. Ra, radius; Ul, ulna; In, intermedium; Fib, fibulare; Ti, tibia; Fi, fibula; Sc, scapula; Hu, humerus.