Fig. 3. Reduced chondrocyte proliferation in the Wnt5a mutant. (A) BrdU labeled cells on sections of the distal humerus of 14.5 dpc embryos are shown. The chondrocyte region is divided into two zones before hypertrophy. Zone I is adjacent to the joint and composed of round cells. Zone II is composed of mostly flattened and columnar chondrocytes adjacent to the prehypertrophic chondrocytes. In the mutant (right), because there are no regular columnar chondrocytes, Zone II is half the region between the Zone I on each end of the cartilage. Zone II was shorter and contained fewer BrdU-labeled cells in the mutant, especially in the central region. The diameter of the cartilage was reduced in Zone I but expanded in Zone II when compared with the wild type. (B) Quantification of BrdU labeling experiments shown in A. Cell proliferation rate was higher in Zone II than in Zone I in the wild-type embryo. In the mutant, proliferation in Zone I was slightly increased, but proliferation in Zone II was reduced by about 30% in the mutant to a level similar to that in Zone I.

Return to article