Pseudostratified columnar epithelium
A pseudostratified epithelium is a type of  epithelium that, though comprising only a single layer of cells, has its cell nuclei positioned in a manner suggestive of stratified epithelia. As it 
rarely occurs as squamous or cuboidal epithelia, it is usually considered synonymous with the term pseudostratified columnar epithelium.

The term pseudostratified is derived from the appearance of this epithelium  in section which conveys the erroneous (pseudo means almost or approaching) impression that there is more than one layer of cells, when in fact this is a true simple epithelium since all the cells rest on the basal lamina. The nucleus of these cells, however, are disposed at different levels, thus creating the illusion of cellular stratification.  Not all ciliated cells extend to the luminal surface; such cells are capable of cell division providing replacements for cells lost or damaged.

Pseudostratified epithelia function in secretion or absorption. If a specimen looks stratified but has cilia, then it is a pseudostratified ciliated epithelium, since stratified epithelia do not have cilia.

Examples 
 Ciliated pseudostratified columnar epithelia is the type of respiratory epithelium  found in the linings of the trachea as well as the upper respiratory tract.
 Non-ciliated pseudostratified columnar epithelia are located in the prostate and membranous part of male vas deferens.
 Pseudostratified columnar epithelia with stereocilia are located in the epididymis. Stereocilia of the epididymis are not cilia because their cytoskeleton is composed of actin filaments, not microtubules. They are structurally and molecularly more similar to microvilli than to true cilia.
 Pseudostratified columnar epithelia are found forming the straight, tubular glands of the endometrium in females.
They are also found in the internal part of the ear.

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