Analysis of lacZ expression within adult organs of tamoxifen-treated HSC-SCL-Cre-ER^T;R26R mice. Mice were injected with tamoxifen (2 mg every 48 hours for 2 weeks), and adult organs were harvested for lacZ analysis one day after the last injection. (A, B) In adult lung, lacZ expression was present in endothelial cells of larger vessels. LacZ activity also was present in smaller lung capillaries. (C) Within adult myocardium, capillaries stained positive for LacZ. (D) Capillaries of intestinal villi and the intestinal wall were LacZ positive. (E) In kidney, scattered LacZ staining was observed within glomeruli and intertubular space. (F) In skeletal muscle, LacZ-positive vessels were present between muscle fibers. Original magnification (panels A, C-F), × 20; (panel B), × 40.