Mammal, trachea (EM, Low)

Structure List Mucous goblet cells Cilia

As one of the principal interfaces between an organism and its environment, the respiratory system serves as a portal of entry for compounds which enter the body via inhalation. As a consequence, bacteria, dust from the inhaled air, and dead cells from the deep lung are carried out to the larynx via a mucociliary escalator. This mucociliary escalator depends on the presence of glycoproteins secreted by airway lining epithelial cells. This scanning electron micrograph illustrates the nature of the ciliary surface once the mucus has been removed. The ciliated cells are interspersed with dome-shaped mucous and Clara cells, which release the secretory product to the surface. The dome-shaped cells with the small holes in them are mucous goblet cells from which granules have been removed during fixation. Note the interspersion of ciliated and nonciliated cells.