Vil1 promoter-driven Cre recombinase expression in the digestive tract varies between transgenic lines. (A, D, G, J, M) Cross sections of tissue from an adult Vil1Cre/1000 R26Ai9/+ mouse show Cre-dependent TdTomato reporter expression (pseudo-colored green) in rare epithelial cells of the glandular stomach, throughout the epithelia of the small and large intestines, and in isolated exocrine cells of the pancreas. No reporter expression was detected in the esophagus. (B, E, H, K, N) Cross sections of tissue from an adult Vil1Cre/20 R26mTmG/+ mouse show Cre-dependent GFP reporter expression (green) throughout the epithelia of the glandular stomach, small intestine, and colon. Extensive GFP expression was also evident throughout the pancreatic parenchyma, except in blood vessels and islets (which retain TdTomato fluorescence [red] and are morphologically distinct). No GFP was detected in the esophagus. (C, F, I, L, O) Cross sections of tissue from an adult Vil1CreERT2/23 R26mTmG/+ mouse 7 days status post a 5-day course of tamoxifen show Cre-dependent GFP reporter expression (green) in subsets of epithelial cells in the small and large intestines. No GFP was detected in the esophagus, stomach, or pancreas. Scale bars = 25 μm.