FGF9-Pitx2-FGF10 signaling controls cecal formation in mice

► Mesenchymal Pitx2 is required for the budding and elongation of the mouse cecum. ► Mesenchymal Pitx2 controls the expression of Fgf10 in the cecum mesenchyme. ► Fgf9 acts upstream of Pitx2 during cecal formation. ► Both epithelial and mesenchymal FGF9 are required for proper cecal development.