basalmembranförtjockning

Basement membrane, also known as basal lamina, is a thin extracellular matrix sheet that underlies epithelial and endothelial cells and separates them from the adjacent connective tissue. It provides mechanical support, maintains tissue architecture, and contributes to cell behavior through signaling cues. Basal lamina and reticular lamina together form the basement membrane; basal lamina is produced primarily by epithelial cells and contains laminins, type IV collagen, nidogens, and proteoglycans such as perlecan, while the reticular lamina, produced by the connective tissue, contains collagen III and other components.

In many tissues, basement membranes are specialized; the glomerular basement membrane acts as part of the filtration barrier in the kidney; alveolar and endoneurial basement membranes serve specialized functions. Basement membranes influence cell adhesion, polarity, migration, and differentiation through interactions with integrins and other receptors. They also guide processes during development and wound healing; degradation and remodeling occur through matrix metalloproteinases.

Pathology: Autoimmune Goodpasture syndrome targets type IV collagen in basement membranes, causing kidney and lung involvement. Alport syndrome is caused by mutations in type IV collagen genes, leading to kidney disease and hearing loss. Diabetic nephropathy involves thickening and structural changes of glomerular basement membrane, contributing to proteinuria. In cancer, basement membrane breakdown enables invasion and metastasis.

In histology, basement membranes are highlighted by PAS staining and are routinely observed with electron microscopy to assess thickness and integrity. The term basement membrane is sometimes used interchangeably with basal lamina; however, basal lamina refers specifically to the epithelial-derived layer, while the basement membrane comprises both basal lamina and the underlying reticular lamina.