Cilia - extend 5 to 7 µm from the surface of the epithelial cells. The dark line at their base is from their basal bodies.
Goblet Cells - scattered cells that secrete mucus. The secretion granules are clustered within the cells. This is seen as a clear circular area due to the mucus being extracted during preparation of the specimen.
Basement Membrane - the epithelium is separated from the underlying connective tissue by a thick basement membrane. It is seen as an acidophilic band beneath the epithelium.
Since it lines the respiratory tract, a pseudostratified ciliated, columnar epithelium with goblet cells is referred to as the "respiratory epithelium".