FIGURE 3.

FGF4 activates the expression of Egr1, Egr2, and tendon-associated collagens. FGF4 (A, B, D, and E) or PBS (C) beads were implanted into the dorsal regions of chick wings of E5 embryos, and the embryos were fixed 48 h later (A–D) or 4 h later (E). Consecutive sections of the FGF4- or PBS-manipulated wings 48 h (A–D) or 4 h (E) after grafting and of the corresponding control left wings (E) were hybridized with Egr1 (A and E), Egr2 (A and E), Scx (A and E), Col1a1 (B and C), Col3a1 (B), Col5a1 (B), Col12a1 (D), and Col14a1 (D) probes. Adjacent sections are grouped accordingly. The asterisks indicate the positions of FGF4 beads in the grafted wings.