Figure 3.

The Runx2ΔC knock-in results in embryonic lethality in homozygotes and absence of clavicles in heterozygotes. (A) Whole animal contact radiographs of 17.5 dpc mice (Faxitron X-Ray, Wheeling, IL). At this age no skeletal elements are detected by soft x-rays in the ΔC/ΔC compared with +/+ and +/ΔC mice. (B) Radiography of 6-wk mice to visualize phenotype of the heterozygote. Shown is a dorsal view of a +/+ mouse with arrow pointing to the clavicle that is missing in the +/ΔC mouse. (C) Staining of skeletons from (17.5 dpc and 18.5 dpc) embryos with Alizarin red to detect bone and Alcian blue to detect cartilage by standard procedures (60).