In biology, columnar refers to the shape of epithelial cells that are taller than they are wide. In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body [1] Form follows function in biology, and columnar morphorphology hints at the functions of the cell. Columnar cells are important in absorption and movement of mucus. The cells may or may not bear microvilli (involved in maximizing the surface area for intestinal absorption) or cilia (involved in moving mucus and trapped material up the respiratory passages to be expectorated or swallowed). Microvilli (singular microvillus) are microscopic cellular membrane protrusions that increase the surface area of cells and are involved in a wide variety of functions including A cilium (plural cilia) is an Organelle found in eukaryotic cells Cilia are tail-like projections extending approximately Columnar epithelium may be simple or stratified. SIMPLE, the S ession Initiation Protocol for I nstant M essaging and P resence L everaging E xtensions, is an instant Simple columnar epithelium is most common and involves one layer of cells attached to a basement membrane. The basement membrane is a structure that supports overlying Epithelial or Endothelial cells. The nucleus is closer to the basal aspect of the cell than the apical aspect. Single stratification tends to indicate absorptive function. Stratified columnar epithelium is rare but can be found in salivary glands. The salivary glands in mammals are exocrine glands that produce saliva It consists of a layer of columnar epithelium resting on top of at least one other layer of eithelial cells, which may have any shape (columnar, cuboidal, or squamous). Cuboidal epithelia are Epithelial cells having a cube-like shape that is their width is approximately equal to their height In Anatomy, squamous epithelium (from Latin squama, "scale" is an Epithelium characterised by its most superficial layer consisting Stratification in cuboidal tissue has a secretory function.
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