(A-C) LacZ expression is detected within mesenchymal cells surrounding small and large bile ducts within Gli1:LacZ reporter mice (n = 3). (D) After tamoxifen induced recombination in Gli1:CreERT2; Rosa26:lox-STOP-lox-tdTomato mice, tdTomato+ cells can be seen wrapping around EPCAM+ cholangiocytes of hilar ducts. (E) Gli1+ mesenchymal cells are seen within the cystic duct of the extrahepatic biliary tree intermingled with CD31+ endothelial cells (F, G). Zoom of (E), where CD31+ endothelial cells (arrowheads) are separate from Gli1+ mesenchymal cells. (H) A few labeled mesenchymal cells can be seen around a peripheral bile duct. (I) Zoom of peripheral bile duct from (H). (J) Gli1+ mesenchymal cells are seen extending to the smaller branches of the biliary tree (arrowhead), but are not observed adjacent to EPCAM+ cells of the canals of Hering (arrow). (n = 5 for D-J). Scale bars, 100 μm.