Tomato expression in E18.5 Fgf10iCre/+; Tomatoflox/+ lungs.

Recombination was induced at E15.5 by a single IP injection of tamoxifen. Note the absence of Tomato expression in Fgf10+/+; Tomatoflox/+ lungs (A; n = 3). The regions in the dotted boxes are magnified in (B) and (C). Tomato-positive cells are observed in the lung mesenchyme and interlobular septae of Fgf10iCre/+; Tomatoflox/+ lungs (white arrows) (A’, B’; n = 3). Inset in B’ shows high magnification of interlobular septae. Labeled cells in the trachea arrange in ring-like structures (black arrows) (C’; n = 3). (A”-C”; n = 8) X-Gal staining of Fgf10LacZ/+ lungs at E18.5. Inset in B” shows high magnification of interlobular septae. Tam: tamoxifen.