Fig. 6. Shhcre;Fgfr1 autopod skeletal phenotype. Autopod skeletons of E18.5 embryos demonstrate consistent patterns that are observed in wild-type (n=4) and mutant (n=6) embryos. Shown within each box are a skeletal preparation of an E18.5 autopod (top left panel), a diagram outlining all elements (top right panel) and a magnified view of the wrist region (lower panel). Brackets indicate regions magnified in lower panels. In a normal autopod, individual digits are numbered and colored differentially. In the mutant, each identifiable digit is assigned the number and color of the corresponding normal digit, while the non-identifiable digits are colored grey. In the magnified views, carpal elements relevant to the identification of digits are labeled with letters: a, trapezium; b, trapezoid; c, central carpal; d, capitate; e, hamate; f, intermediate cuneiform; g, lateral cuneiform; h, cuboid; i, navicular. The metacarpals/metatarsals and carpals/tarsals are outlined with broken lines to delineate the connections between them. In both mutant forelimb and hindlimb, digits 1 and 5 are easily identifiable based on their phalanx number, digit length and their metacarpal/metatarsal articulation with the carpals/tarsals. Digit 2 is identified in the mutant forelimb based on its length (shorter than digits 3, 4 and longer than 1, 5), and more importantly on its metacarpal articulation with both the trapezoid (b) and central carpal (c). The grey digit in the mutant forelimb is either a digit 3, 4 or a chimeric 3/4 based on its length (longest of all) and its articulation with both the capitate (d) and the hamate (e). Digit 4 is identified in the mutant hindlimb based on its articulation with the Cuboid (h). The grey digit in the mutant hindlimb is either a digit 2, 3 or a chimeric 2/3 as it articulates with the fused intermediate/lateral cuneiform (f/g) atop the navicular (i). FL, forelimb; HL hindlimb.