Basement membranes are heterogeneous, highly specialized, electron-dense structures constructed from components of extracellular matrix proteins 20 to 200nm in width. They provide anchorage for adjacent cells as well as stimuli for cell differentiation, cell migration, and cell phenotype. These functions provide basement membranes with an important role in embryonic development and tissue repair. Basement membranes are responsible for tissue compartmentalization and the maintenance of tissue architecture. In addition, they are barriers for the filtration of macromolecules. This latter function is particularly apparent for the glomerular basement membrane (GBM), which serves as the filtration barrier between the lumen of the glomerular capillaries and the Bowman's space within the renal glomerulus. Basement membranes are normally produced and deposited by adjacent cells which then remain anchored to the extracellular matrix via interactions with specific cellular receptors [1–5].