Fig. 3. Expression of Bmp4, Shh and Bmp2 was downregulated in the anterior region of the Msx1^–/– palatal shelves, but was restored in the Msx1^–/–/Tg palatal shelves. (A) Bmp4 expression was downregulated in the Msx1^–/– palatal mesenchyme, but remained in the epithelium (arrow) at E12.5. (B) At E13.5, Bmp4 expression was not detected in the Msx1^–/– palatal mesenchyme. (C) Endogenous Bmp4 expression was not detected in the Msx1^–/–/Tg palatal mesenchyme at E13.5, indicating that transgenic Bmp4 did not induce endogenous Bmp4 expression in the absence of Msx1. (D-F) Shh expression remained unaltered in the MEE (arrow) of the E12.5 Msx1^–/– palatal shelf (D), but was not detectable in the MEE (arrow) of the E13.5 palatal shelf (E). (F) However, Shh expression was restored in the MEE (arrow) of the E13.5 Msx1^–/–/Tg palatal shelf. (G-I) Bmp2 expression was detected in the E12.5 Msx1^–/– palatal shelf (G), but was downregulated in the palate at E13.5 (H). In the E13.5 Msx1^–/–/Tg palatal shelf, Bmp2 expression was again detected (I). Scale bar, 100 µm.