Fig. 7. Hhip and Ptch (Hip1 and Ptch1 in figure) regulate mesenchymal-epithelial interaction in posterior stomach. Stomach morphology and gene expression in mutant embryos were analyzed at E12.5. Strong expression of Isl1 is observed in posterior stomach of Hhip^+/+;Ptch^+/– mice (A). Homozygous Hhip mutants display reduced Isl1 expression (B) that is further diminished in Hhip^–/–Ptch^+/– embryos (C). Morphometric analysis of posterior stomach mesenchyme and epithelium reveals no change in epithelial or mesenchymal area in Hhip^+/+;Ptch^+/– mice compared with wild type controls (D, blue columns; Hhip^+/+;Ptch^+/+, n=7; green columns; Hhip^+/+;Ptch^+/–, n=4). By contrast, gradual epithelial thinning and mesenchymal thickening is in observed in Hhip^–/– and Hhip^–/–;Ptch^+/– embryos (red columns; Hhip^–/–;Ptch^+/+, n=4; yellow column; Hhip^–/–;Ptch^+/–, n=4; #no significant difference, *P<0.05, **P<0.01). Error bars shown are ±s.d.