Fig. 2. Ablation of COUP-TFII in the mesenchyme of the developing stomach using Nkx3-2^Cre and COUP-TFII floxed mice. (A) Whole-mount X-gal staining of Nkx3-2^Cre/+; COUP-TFII^flox/+ embryo, demonstrating the ablation of COUP-TFII by Nkx3-2Cre at E9.5 is shown. lacZ expression represents Cre-mediated recombination of floxed COUP-TFII. (B) The expression of Nkx3-2Cre at E9.5 was detected by whole-mount X-gal staining of Nkx3-2^Cre/+; ROSA26R/+ embryo. X-gal staining represents Cre-mediated ablation of an interfering stop sequence in the ROSA26 reporter gene. Specific staining was observed in the developing stomach of both embryos. (C) A partially dissected Nkx3-2^Cre/+; COUP-TFII^flox/+ embryo was stained by whole-mount X-gal staining, then paraffin embedded and serially sectioned. X-gal staining indicates Cre-mediated recombination and was detected throughout the gastric mesenchyme, but not in the epithelium, demonstrating the ablation of COUP-TFII in the gastric mesenchyme at E12.5. Scale bars: in B, 100 µm for A,B; in C, 100 µm for C.