Figure 3.

Expression and function of BMP signaling components in vivo. (A) Section in situ hybridizations were performed, at brachial levels, with digoxigenin-labeled riboprobes to collagen IX (a), BMP-RIB (b), BMP7 (c), and BMP4 (antisense probe shown in d, sense in e). In each panel, the notochord is indicated with an arrowhead. (B) Somites of E3 chick embryos were injected unilaterally with RCAS-Noggin virus, and analyzed on E8. a shows alcian blue staining of a typical infected embryo; cartilage deletions are indicated by arrowheads. (b,c) Adjacent, post-thoracic-level sections from an infected embryo, analyzed for cartilage (blue) and viral gag protein (brown; b), or Pax1 mRNA (purple, c).