Figure 2.

Histological analyses of tracheal epithelia in adult male K14-rtTA/TRE-Cre/DE3 mice of various genotypes receiving standard chow. These genotypes included wild-type (WT) (A and H), Cre⁺ (B and I), rtTA⁺ (C and J), and BiTg (D and K). (A–D) Tracheal sections were stained for basal-cell markers K5 and K14 (K5 in red, and K14 in green). (H–K) Tracheal sections were stained for Clara-like and ciliated cell markers CCSP and acetylated tubulin (ACT) (CCSP in red, and ACT in green). Normal CCSP staining (yellow arrow) was evident in WT and rtTA⁺ genotypes (H and J), whereas large goblet-shaped CCSP⁺ cells (white arrow) are present in Cre⁺ and BiTg genotypes (I and K). (E, F, L, and M) We performed a morphometric analysis of WT versus BiTg mice receiving standard chow. The nuclear volume density/surface density (Vv/Sv, i.e., total cell mass) was decreased in BiTg (E). K5⁺ cells were decreased approximately threefold in BiTg (F), and CCSP⁺ cells were decreased approximately eightfold in BiTg. No significant difference was evident for K14⁺ cells (G) and ACT⁺ cells (M). Significance was established at P ≤ 0.05. Dox, doxycycline.