Fig. 7. Comparative expression pattern of signaling molecules in wild-type (A,C,E,G,I,K,M,O,Q,S) and Hoxa5^–/– (B,D,F,H,J,L,N,P,R,T) E12.5 stomachs. Sagittal sections were oriented with hindstomach and forestomach from left to right. Arrowheads indicate the limits of the domain of high expression when appropriate. Shh (A,B) and Ihh (C,D) displayed reciprocal expression gradients in the gastric epithelium. They were expressed in the fore- and hindstomach, respectively. Compared with wild-type samples, high expression of Shh was more restricted in Hoxa5^–/– stomachs. In contrast, Ihh expression extended more in the forestomach. Expression of Hh receptor Ptc (E,F) and its downstream effector Gli (G,H) was enhanced in Hoxa5^–/– stomachs. Fgf10 transcripts were confined to the mesenchyme of the hindstomach in wild-type samples (I), while in Hoxa5^–/– mutants (J), they spread into the forestomach. Bmp4 expression (K,L) was reduced particularly in the hindstomach of mutants. In controls, Tgfb1 expression was confined to the peri-epithelial zone of the stomach mesenchyme (M, inset). In mutants, Tgfb1 expression was more disseminated throughout the mesenchyme (N, inset). A gain of Tgfb3 expression was observed in the mutant mesenchyme (O,P). In contrast, Barx1 expression decreased in the mutants (Q,R). Nkx2.5 expression in the pylorus region was unaffected by the lack of Hoxa5 function (S,T, arrows). d, duodenum; e, esophagus. Scale bar: 100 µm.