Cell Cards: Submucosal Glands
A, B, C, D, and F. Images of tissue isolated from a 4-year-old human lung. A) H&E of a SMG opening into airway surface epithelium (SE). Regions of the SMG are indicated: terminal ciliated duct (TCD), collecting duct (CD), mucous tubules (MT) and the predominant cell types: mucous cells (MC), myoepithelial cells (MEC) and serous cells (SC). B-F. Immunofluorescent imaging of cell types within the terminal ciliated duct (B), mucous collecting duct (C), mucous tubule (D), surface airway epithelium (E-F) and distal SMG acini (E-G ) showing expression of MUC5B in mucous cells, KRT14 and ACTA2 in myoepithelial cells , and TUBA4A in ciliated cells. KRT5 is expressed in basal cells of the surface airway and is co-expressed with KRT14 in SMG myoepithelial cells cells. SOX2 is expressed in some epithelial cells in the surface airway and in the SMG. SOX9 is predominantly expressed in SMG cells. Insets are higher magnification images of boxed regions.
Second-Harmonic Generation
Visualization of a submucosal gland. ACTA2 stains myoepithelial cells. MUC5B stains the mucin made by goblet cells inside the gland surrounded by a collagen matrix detected by (SHG)
Panel 1: 2D image of a single Z-stack frames (Click to play video of rendered z stacks in larger popup window)
Panel 2: 3D surface rendering in Imaris showing the goblet cells using Imaris software. (Click to play 3D video in larger popup window)
2D rendering of the Z-stacks showing the MUC5B expressing goblet cells (red) , ACTA2 expressing myoepithelial cells (green), and collagen from the second harmonics (white) confocal imaging.
3D surface rendering of the MUC5B expressing goblet cells (red), the ACTA expressing myoepithelial cells (green), and collagen from the second harmonics (white) confocal imaging.
Terminal Ciliated Duct
The opening of the terminal ciliated duct into the bronchiolar epithelium demarcates the location of a submucosal gland (SMG). These are present in a density of ~1 per mm2 of airway surface epithelium. In humans, the greatest density can be found in the trachea and within the first four airway generations. In mouse, all SMGs are found lining the cricoid cartilage of the larynx and within the first few cartilaginous rings of the trachea. The length of the terminal duct is highly variable dependent on both the size and location of the gland. The function of this duct is expulsion of the products made by the gland into the airway. The basal and epithelial cells lining the terminal ciliated duct can appear as a monolayer, as well as have a pseudostratified appearance.
Myoepithelial Cells
| A contractile cell found between secretory cells and basement membrane of the seromucus glands located in the submucosa of the upper trachea in the mouse. Each myoepithelial cell has long cytoplasmic processes that wrap around a secretory unit (acinus, or smalll cluster of cells with a central lumen). The contraction of the myoepithelial processes forces the secretory product from the secretory unit into its duct. Wikipedia |
