Ans. a. Type III collagen is present Type IV collagens (not the type HI collagen) 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 flat lamellar "chicken wire" mesh (although labeled as a membrane; it is quite porous). The major constituents are amorphous nonfibrillar type IV collagen and lantinin." '"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