Columnar Epithelium Histology Characteristics
Columnar Epithelium is a form of epithelium that is of a general columnar or prismatic shape. These cells possess a single nucleus and a cytoplasm that is usually distinctly granular. They are arranged with their long axes parallel to each other, so that their free ends form the surface of the epithelium, while their deeper cuds either rest upon the tissues beneath the epithelium or upon other epithelial cells of different shape which form one or more layers between the columnar cells and the underlying tissue. When they rest directly upon the tissues beneath there are usually other epithelial cells of a pyramidal or oval shape which may be regarded as immature cells ready to take the place of such fully developed cells a> may become detached or destroyed. The presence of these cells occasions a narrowing of the deep ends of the columnar cells, so that they are not strictly prismatic in form. In cross-section, or when viewed in a direction parallel to their long axes, the cells have a polygonal form due to the lateral pressure they exert upon each other.
The nuclei of the columnar cells are oval, situated nearer the base of the cell than its superficial end with their long axes parallel to those of the cells themselves, and are vesicular in structure with a distinctly reticular arrangement of the chromatin filaments.
Columnar epithelium is found chiefly upon the free surfaces of mucous membranes, but also occurs in some of the secreting glands.
The minute structure of the cells varies somewhat in different situations, but the consideration of these minutiae must be deferred until a description of the structure of the different organs is found in other sections see: Histology $infernoexternal->display_block('epithelium'); ?>