PSEUDOSTRATIFIED COLUMNAR EPITHELIUM

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    This type of epithelium consists of tall cells and short cells. All cells of the pesudostratified columnar epithelium rest on the basement membrane but all of them do not reach the free surface of the epithelium. Only the tall columnar cells extend through the entire thickness of the epithelium. Each of these cells has a wider part which reaches the free surface of the epithelium and a narrow and slender basal part which passes downward to rest on the basement membrane. The short cells also called basal cells, lie between the columnar cells. The basal cells are conical in shape having a broad base which rests on the basal lamina and a tapering upper part which terminates between the columnar cells and does not reach the free surface of the epithelium. As the cell nuclei are located in the wider parts of both types of the cells of the pseudostratified columnar epithelium they are present in the apical part of the tall cells and basal parts of the short cells. The nuclei of all the component cells of the epithelial sheet do not lie at the same level. The nuclei appear to be present in two or more rows. This arrangement creates a false appearance of cell stratification. Accordingly, the epithelium is titled as pseudostratified.
Falsely stratified '' pseudo is a combining form meaning false''.

Pseudostratified Columnar Epithelium 


The pseudostratified columnar epithelium lines the conducting part of the respiratory system {nose, nasopharynx, trachea, and bronchi} .
 It also lines the major male genital ducts {duct of epididymis and ductus deferens}

The tall cells of the pseudostratified epithelium usually exhibit special structural modifications on their apical surface '' kinocilia in the in the conducting respiratory passages and stereocilia in the male genital ducts''.

NOTE :Because all cells of the pseudostratified columnar epithelium rest on the basement membrane, some authorities consider this epithelium to be a subtype of the simple <unilaminar> epithelia.

Found In :

  • Rispiratiry System 
  • Reproductive System 

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