Figure 1.

Comparative Analysis of Mouse and Pig Limb Bud Development

(A) Phylogenetic tree of Artiodactyla.

(B) Developing mouse and pig (Sus scrofa) forelimb skeletons at equivalent embryonic stages (mouse: embryonic day [E] 13.75; pig: gestational day [D] 33). Cartilage is stained with Alcian blue and bone with alizarin red.

(C) Mineralization pattern of the mouse (E17.5) and pig (D55) handplate skeleton. Digits are numbered from 1 to 5 (mouse) and II to V (pig) from anterior to posterior. s, scapula; h, humerus; r, radius; u, ulna; c, carpals; m, metacarpals; p, phalanges.

(D–L) Whole-mount RNA in situ hybridization (ISH) analysis of mouse and pig forelimb buds at equivalent developmental stages.

(D) Expression of Gli3 and Hand2 in mouse (E9.5) and pig limb buds (D18).

(E–I) Spatial distribution of Shh (E), Fgf8 (F), Grem1 (G), Hoxd12 (H), and Hoxd13 (I) transcripts in mouse (E10.5) and pig forelimb buds (D21). Black arrowheads indicate the limb bud apex. A white arrowhead points to the anterior Grem1 expression in pig limb buds (left panels in G). Black arrows point to the gap between the dorsal (d) and ventral (v) Grem1 domains in limb bud apices (right panels in G).

(J–L) Expression of Hoxd11 (J), Hoxd12 (K), and Hoxd13 (L) in mouse (E11.75) and pig (D24) handplates. Black arrowheads indicate the anterior Hoxd11 expression domain in pig handplates.

Pig gene names are not capitalized for simplicity. n = 2 per stage for all pig ISH probes and skeletal stainings; n = 3 per stage for all mouse ISH probes and skeletal stainings. All limbs shown are oriented with anterior to the top, except right panels in (G). Scale bars, 1 mm (B and C) and 0.25 mm (D–L).

See also Figures S1 and S2.