Figure 1

Skeletal defects in Mstn^-/- Gdf11^-/- newborn mice. Thoracic region of Gdf11^-/- (A) and Mstn^-/- Gdf11^-/- (B) mutants showing the increase in rib number. Note that the anterior homeotic transformations of thoracic vertebrae are more extensive in the Mstn^-/- Gdf11^-/- mutant (20 ribs) versus the single Gdf11^-/-mutant (18 ribs). Whole skeleton preparation of Gdf11^-/- (C) and Mstn^-/- Gdf11^-/- (D) pups. (E) Ventral torso of newborn double mutant showing multiple projections from the skin (*) and an extra limb (arrowhead). Forelimb skeleton preparations of Gdf11^-/- (F) and Mstn^-/- Gdf11^-/- (G and H) pups showing an extra bone emanating from the shoulder of the double mutant (G, arrow) and an extra limb (H). The limb in (G) has been rotated for a better view of the extra bone. (I and J) Hindlimb phenotypes of Mstn^-/- Gdf11^-/- pups. Note the truncation of the vertebral column (I) and malformation of the ilieum and all leg bones (J).