rakuvälise maatriksi erivorm, mis koosneb omavahel läbipõimunud kollageen IV ning erinevate laminiini isovormide, nidogeeni ja sulfeeritud proteoglükaanide võrgustikust, The basement membrane is a thin, fibrous, extracellular matrix of tissue that separates the epithelium (skin, respiratory tract, gastrointestinal tract, etc.), mesothelium (pleural cavity, peritoneal cavity, pericardial cavity, etc.) and endothelium (blood vessels, lymph vessels, etc.) from underlying connective tissue. As seen with electron microscope, the basement membrane is composed of two layers, the basal lamina and the underlying layer of reticular connective tissue. The underlying connective tissue attaches to the basal lamina with collagen VII anchoring fibrils and fibrillin microfibrils. The two layers together are collectively referred to as the basement membrane.