Cartilage overgrowth at the jaw joint in nkx3.2 mutant zebrafish. (A,B) Ventral views of dissected pharyngeal skeletons stained with Alcian Blue (cartilage) and Alizarin Red (bone) at 60 dpf. Insets with further dissections of the boxed regions in A and B demonstrate the wild-type retroarticular cartilage in A and the cartilage overgrowth at the site of the fused jaw joint in nkx3.2 mutants in B. (C,D) Frontal H&E-stained sections through 60 dpf jaw joints show fusion of the jaw joint and cartilage overgrowth in nkx3.2 mutants. (E-J) In wild types at 21 dpf (E,G,I), PCNA+ cells are present largely on the lower jaw side of the jaw joint, and PCNA+ and BrdU+ chondrocytes are present in the proliferative zone of the ceratohyal. In nkx3.2el802 mutants (F,H,J), proliferating chondrocytes marked by BrdU (E,F) and PCNA (G-J) are present across the fused jaw joint region. (K) Quantification of PCNA+ cells per total nuclei stained with Hoechst. Individual animals are plotted (dots) with mean±s.d. CH, ceratohyal; JJ, jaw joint; LJ, lower jaw; M, Meckel's cartilage; PQ, palatoquadrate; UJ, upper jaw; WT, wild type. Scale bars: 500 µm (A,B); 50 µm (C-J).
|
