n. (pl. microvilli) one of a number of microscopic hairlike structures (about 5 ?m long) projecting from the surface of epithelial cells (see epithelium). They serve to increase the surface area of the cell and are seen on absorptive and secretory cells. In some regions (particularly the intestinal tract) microvilli form a dense covering on the free surface of the cells: this is called a brush border.
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