Figure 6.

Lineage tracing of ACTA2-Cre^ERT2 and smooth muscle myosin heavy chain 11 (MYH11)-Cre^ERT2 labeled myoepithelial cells at various points after birth. ACTA2-Cre^ERT2:ROSA-TG and MYH11-Cre^ERT2:ROSA-TG mice were induced with tamoxifen by gavage every other day (EOD) from birth to 18 days or by a single intraperitoneal injection of tamoxifen on Days 3, 5, or 7 after birth. Tracheas were then harvested at 21 days and immunofluorescently stained for SMMHC, αSMA, GFP, and/or tdTomato, as indicated. DAPI was used to mark nuclei. (A–D) Representative low-power images of SMGs from ACTA2-Cre^ERT2:ROSA-TG mice with higher-power merged and single-channel images of the boxed region on the right. (E–H) Representative low-power images of SMGs from MYH11-Cre^ERT2:ROSA-TG mice are shown with higher-power merged and single-channel images of the boxed region on the right. (I–K) Morphometric analysis of the studies in (A–H) showing (I) the percentage of SMG cells staining GFP⁺, (J) the number of GFP⁺ cells per section, and (K) the percentage of GFP⁺ glandular cells that did not express αSMA or SMMHC. Data depict the mean ± SEM of n = 5–7 mice evaluated. Asterisks denote significance levels using two-way ANOVA with Bonferroni’s multiple comparison post-test: *P < 0.05; **P < 0.01; and ****P < 0.0001. ns, not significant. Significance marks compare the EOD condition to each single-pulse conditions for ACTA2-Cre^ERT2:ROSA-TG (black text) and MYH11-Cre^ERT2: ROSA-TG (red text) mice. Scale bars: 25 μm.