CKO of Hif-1α in limb bud mesenchyme alters the formation of wrists. H&E staining of newborn (NB; A and B) and P9 (C and D) wrists and skeletal preparation of P9 wrists (E and F) show that bones present in the CKO wrist are misshapen, dislocated, and partially fused together for some of them. Wrist bones are indicated on each section. 1–3 and 4/5, distal row of carpal bones; c, central carpal bone; r and u, radial and ulnar bones; Ra and Ul, radius and ulna. Slashes between bone designators (i.e., 4/5) indicate a fusion of the indicated bones. 4/5, but never c/3, are always fused in wild-type wrist.