<prompt> Which of the following types of collagen is present in basement membrane?Type IType IIIType IVType V  <response>: Ans. c. Type IV Ref: Robbins 9e p20-23. 8e p95Type IV collagens are the main components of the basement membrane, together with laminin.The basement membrane is synthesized by contributions from the overlying epithelium and underlying mesenchymal cells, forming a fiat lamellar chicken wire mesh although labeled as a membrane, it is quite porous. The major constituents are amorphous nonfibrillar type IV collagen and laminin. --Robbins 9e p21.Type IV collagens have long but interrupted triple-helical domains and form sheets instead of fibrils; they are the main components of the basement membrane, together with laminin.--Robbins 9e p23 Main Types of Collagens, Tissue Distribution, and Genetic DisordersCollagen TypeTissue DistributionGenetic DisordersFibrillar CollagensIUbiquitous in hard soft tissues Bone, cornea myofibrilsQOsteogenesis imperfecta; Ehlers-Danlossyndrome-arthrochalasias type IIICartilage, intervertebral discQ, vitreousQAchondrogenesis type It, spondyloepiphysea dysplasia syndromeIIIHollow organs, soft tissues, granulation tissueQVascular Ehlers-Danlos syndromeVSoft tissues, blood vesselsQClassical Ehlers-Danlos syndromeIXCartilage, vitreousQStickler syndromeBasement Membrane CollagensIVBasement membranes, eye lensQAlport syndromeOther CollagensVIUbiquitous in microfibrilsBethlem myopathyVIIAnchoring fibrils at dermal-epidermal junctionsQDystrophic epidermolysis bullosaIXCartilage, intervertebral discsQMultiple epiphyseal dysplasiasXVIITransmembrane collagen in epidermal cellsQBenign atrophic generalized epidermolysis bullosaXV XVIIIEndostatin-forming collagens, endothelial cellsQKnobloch syndrome type XVIII collagen 