Basement membranes are specialized extracellular matrices that are comprised of several biological components including collagens, laminins, and proteoglycans. They form thin continuous sheetlike structures that separate epithelial tissues from the adjacent connective tissue stroma; thus, they form barriers, which block the passage of cells and other macromolecules. The basement membranes become permeable during tissue development, repair, and at sites of inflammation, to allow immune cells to reach the site (1 ).
