Simple columnar epithelium

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Structures and types of simple epithelia.

Simple columnar epithelium consists of a single layer of cells that are taller than they are wide, with an oval nucleus usually located towards the basal region of the cell. As its name suggests, the cells of this epithelium have a column-like appearance in sections perpendicular to the basement membrane. There are two functionally different types of simple columnar epithelium: ciliated and nonciliated.

The ciliated simple columnar epithelium bears cilia (finger-like projections of the plasma membrane) on the apical surfaces of cells, with goblet cells usually scattered throughout the epithelium. Up to 300 cilia may be present on each cell, beating in a synchronized manner with adjacent cells to propel materials over the surface of the epithelium. This epithelium lines the lumen of the uterine tubes, aiding in the movement of ova from the ovary to the uterine cavity.

Nonciliated simple columnar epithelium, on the other hand, has no cilia but typically has microvilli, which are small cytoplasmic projections on the apical surface of cells. As well, there are goblet cells interspersed within the epithelium. Microvilli serve to increase the surface area of the epithelium for secretion of mucin and enzymes and absorption of nutrients. They often appear all together on light microscopy as a dark fuzzy structure rather than distinct individual structures and are therefore collectively called a brush border.  Nonciliated simple columnar epithelium is principally found in the digestive tract and is mainly involved in absorption, for example, in the small intestine and secretion such as in the stomach.