Whole-mount in situ hybridization was performed on E12.5 and E13.5 embryonic GI tracts from wild-type (WT), Fgf9−/− and Fgf10−/− embryos. (A–D) At E12.5 and E13.5, Bmp4 was expressed strongly in the cecal mesenchyme in WT tissue (A,B) and Fgf10−/− tissue (C,D). (E,F) At these same stages, Bmp4 expression was absent in Fgf9−/− cecum. (G,H) At E12.5, Shh was expressed in cecal epithelium in WT tissue, and its expression was not significantly affected by the absence of expression of either Fgf9 or Fgf10.