Alizarin red and alcian blue stained adult skeletons. Alizarin red and alcian blue stained (A-F) thoracic and (G, H) lumbar vertebrae. (B, C) Split vertebrae (arrowhead), fused vertebrae (arrow) and reduced costal heads of ribs (asterisks) compared to (A) wild-type animals are found. (D-F) Dorsal examinations exhibit reduced spinous processes, open neural arches (white arrowheads) and reduced (black arrowheads) or malformed (black and white arrows) intervertebral joints. (G, H) Reduced intervertebral joints occur in (H) transgenic mice compared to (G) wild-types but no fused adjacent neural arches (dashed lines) are observed. iap, inferior articular process; ivd, inter-vertebral disc; la, lamina; p, pedicle; pr, proximal rib; sp, spinous process; sap, superior articular process; TG, transgenic; tp, transverse process; vb, vertebral body; WT, wild-type.