Fig. 2.

TAK1 indirectly regulates columnar chondrocyte organization and the progression of terminal maturation. (A) Immunoblot for TAK1 protein isolated from humerus cartilage of E14.5 wild-type and Tak1^Prx embryos. (B) Histology and in situ hybridization of E14.5 wild-type and Tak1^Prx humerus sections for H&E (B1, B2), Ihh (B3, B4), Col10a1 (B5, B6), and Mmp13 (B7, B8). (C1–C4) Double-sided arrows indicate hypertrophic region. H&E staining of proximal humerus from wild-type (C1, C3) and Tak1^Prx (C2, C4) embryos at E18.5. Black boxes (C1, C2) indicate region of ×20 magnification. (C3, C4) Brackets denote height of columnar zone of chondrocytes. In situ hybridization of E18.5 wild-type and Tak1^Prx humerus sections for Ihh (C5, C6), Col10a1 (C7, C8), and Mmp13 (C9, C10). (D) BrdU incorporation of E14.5 and E18.5 wild-type (blue bars) and Tak1^Prx (red bars) embryos. (E) Quantitation of TUNEL⁺ cells in the proximal humerus at E18.5 (^ap < .05 versus wild type).