Figure 1.
α-Smooth muscle actin–positive (αSMA+) and smooth muscle myosin heavy chain 11–positive (SMMHC+) cells emerge during the elongation phase of submucosal gland (SMG) morphogenesis. Gt(ROSA)26Sortm4(ACTB-tdTomato,-EGFP)Luo (ROSA-TG) mice were harvested at 3, 5, 7, and 21 days after birth. Tracheal sections were immunofluorescently stained for (A–D) αSMA or (E–H) SMMHC. Representative images for each stain were taken for placode (phase 1), elongation (phase 2), branching (phase 3), and differentiation (phase 4) phases of SMG development. Single-channel images of αSMA and SMMHC are below each of the merged panels. Arrows in A and E mark the glandular placode. Scale bars: 25 μm.