Pseudostratified columnar epithelium gets its name because while the cells are columnar in shape, their nuclei do not arrange at the bottom (or basal side) of the cell. Rather the nuclei are arranged in an almost random fashion. However, they are true simple epithelium because it is only a single layer of cells, and the “stratification” is just an illusion. They are found usually in the upper respiratory tracts such as trachea and a distinctive feature is the cilia that are present on the apical side of the epithelium.
Its function is in secretion and absorption. In the airway, the cilia also function to trap dust and to propel mucus.
Trachea, highlighting the pseudostratified columnar epithelium. Notice the nuclei are not all at the same level, the presence of two goblet cells that secrete mucus, and cilia on the apical side of the epithelium. Annotated version here. (TM: 630x, picture taken with a Zeiss Planapo 63/1.4 Oil on Sony A7ii)Bronchus, highlighting the pseudostratified columnar epithelium with cilia on the apical side. (TM: 630x, picture taken with a Zeiss Planapo 63/1.4 Oil on Sony A7ii)
There is also the non-ciliated type that can be found in portion of the male reproductive tract.
Pseudostratified columnar epithelium in vas deferens. Apical structures are classified as stereocilia because of its components. (TM: 630x, picture taken with a Zeiss Planapo 63/1.4 Oil on Sony A7ii.)Pseudostratified columnar epithelium in rat epididymis. Apical structures are classified as stereocilia because of its components. (TM: 630x, picture taken with a Zeiss Planapo 63/1.4 Oil on Sony A7ii)
Kit Ng, Ph.D. 