Fig. 6. Expression of Axin2 in developing skull. The Axin2 expression pattern was visualized by ß-gal staining in whole mounts (A-H) or sections (I-L). Axin2 is present in metopic and coronal sutures at E16.5 (A,E,I). Axin2 is detected at high levels in the osteogenic fronts (arrowheads), periosteum (asterisks) and mesenchyme of the sutures, as well as in the nasal bone (arrows) and nasal cartilage. At P4, Axin2 is highly expressed in the osteogenic fronts (arrowheads), periosteum (asterisks), nasal bone (arrows) and nasal cartilage (B,F,J). At P14, high levels of Axin2 are observed in nasal and frontal bones (C,G) in addition to the osteogenic fronts (arrowhead) and periosteum (asterisks; K,L). By P31, expression of Axin2 appears to be diminished to very low levels (D,H). First and second rows, the Axin2^lacZ allele shows Axin2 expression. Third row, coronal sections of the ß-gal stained metopic sutures, counterstained with nuclear Fast Red. Scale bars: 3 mm in A,H; 5 mm in B-D; 1 mm in E,F; 2 mm in G; 100 µm in I-L.