basal lamina

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basal lamina One of two layers (the other is the reticular lamina) that form the basement membrane. It is an amorphous, or filamentous, sheet of material that underlies epithelial cells (see EPITHELIUM), composed of a special kind of collagen and a carbohydrate. In addition to support, it is thought to provide a barrier controlling the exchange of molecules between the epithelial layer and underlying tissue.