Induction of SBECs in aged and young mice following influenza pneumonia. A. The percentage of total SBEC-containing bronchioles (both SCGB1A1+ and SCGB1A1- subset) in aged (square) and young (triangular) mice following influenza infection. B. The percentage of SCGB1A1+ SBEC-containing bronchioles in the aged (solid column) and the young (open column) mice. C. The percentage of SCGB1A1- SBEC-containing bronchioles in the aged (solid column) and the young (open column) mice. Ten aged and 10 young mice were used for each time-point. All error bars represent standard errors. *p < 0.05, **p < 0.01 by Student t-test. D-K. Representative immunofluorescent staining of lung sections for SCGB1A1 (green) and pro-SPC (red) at the indicated time-points following influenza infection (DAPI staining not shown). The boxed areas in D and H are shown at higher magnification in E and I, respectively. Solid and open arrowheads point to SCGB1A1+ and SCGB1A1- SBECs, respectively. Scale bars are 500 μm for the low magnification images, and 50 μm for the high magnification images.