Pseudostratified Columnar

Cell Shape

The cells are columnar in shape.  Remember that this shape, columnar, is a 3D shape. It will look like a rectangle or a square in a 2D representation. The appearance depends on whether the cell is cut in a transverse planeA horizontal plane dividing the body into upper and lower parts. or in a longitudinal plane.  In pseudostratified columnar epithelium, the columns seem to have tumbled over. They appear to be laying on top of each other.  Nuclei will all appear to be toward the basal surface of the cells, but they will be at different heights (as compared to simple columnar where all the nuclei are at the same distance from the basal surface)

Layering

This type of epithelia appears to have multiple layers of cells but does not.  All the cells touch the basement membrane.  The prefix “Pseudo” is used to indicate a false impression. It suggests that the appearance of this tissue as layered is incorrect.   In pseudostratified columnar epithelium, the columns appear disorganized. They seem to have tumbled over and are lying on top of each other.  

Function

Pseudostratified columnar epithelium often contains goblet cells, which secrete mucus.  Mucus is essential in mucus membranes exposed to the drying forces of air. These include the respiratory, digestive, urinary, and reproductive tractsBundles of nerve fibers in the CNS that carry signals between brain regions.. These mucus secretions can have varying purposes. They can lubricate passing food, trap inhaled particles, or create a mucus-rich barrier between stomach juices and the cells.

Locations

Pseudostratified columnar epithelium is typically found lining parts of the respiratory tract, such as the trachea and larger bronchiThe large airways that branch from the trachea into the lungs, dividing into smaller bronchioles..  It can be found in reproductive tubes such as the ductus deferens and the uterine tubesAlso called fallopian tubes, they transport the oocyte to the uterus..

Specializations

Many pseudostratified columnar epithelial cells possess ciliaHair-like projections on the surface of some cells that move fluids or particles. on their apical surfaces. These cilia beat rhythmically to move the layer of mucus.  In the trachea, the cilia move trapped debris up the trachea. They then transport it into the pharynxThe muscular passageway connecting the mouth to the esophagus and larynx. (throat), where it is swallowed into the digestive system.  In the ductus deferens and uterine tubes, the cilia help move sperm and ovulated ovumA mature egg cell to their destination.