Fig. 2. Jaws^-/- embryos exhibit delayed chondrocyte maturation. (A) Histological and radioactive in situ hybridization analysis of chondrocyte maturation in the humerus (E14.5). Top panels show sections stained with Alcian Blue and nuclear Fast Red (AB/NFR). White brackets indicate the separation of wild-type prehypertrophic zones, which remain continuous in the Jaws^-/- embryo (vertical lines). Arrows indicate reduced Ptch1 and Pthrp signals in periarticular chondrocytes. (B) Radioactive in situ hybridization analysis showing delayed terminal hypertrophic chondrocyte differentiation in the Jaws^-/- humerus (E15.5), evidenced by decreased expression of Mmp13 and osteopontin. White brackets indicate the separation of wild-type Col10a1-positive hypertrophic zones, which remain continuous in the Jaws^-/- embryo (vertical line).