Figure 2.

Mutation of E2f4 causes defects in early embryonic cartilage and bone development. Alizarin Red (bone) and Alcian Blue (cartilage) staining of (A) e13.5 and (B) e15.5 embryos. e13.5 E2f4^-/- embryos exhibit less ossification in the clavicles, n ≥ 2 (arrowheads). e15.5 E2f4^-/- embryos display less ossification of bone (arrowhead) and less deposition of cartilage matrix in the presphenoid and basisphenoid elements, located below the cranial vault, n ≥ 4. Abbreviations: bs, basisphenoid; ps, presphenoid.