Which type of collagen is associated with blood vessels and parenchymal cells?

• A. Type I
• B. Type IV
• C. Type II
• D. Type III

Answer: (C)

Collagen that lines basement membranes around vessels and supports the surfaces where parenchymal cells sit is type IV. This form forms a flexible, sheet-like network rather than thick fibers, creating the basement membrane that endothelial and epithelial cells rest on and that surrounds blood vessels. Because it forms these non-fibrillar networks, it provides a stable yet permeable foundation for the cells in organs and vessels. In contrast, fibrillar collagens like type I and type II build strong fibers in bone, skin, and cartilage, while type III forms reticular, delicate scaffolds in soft tissues. The basement membrane–associated type IV collagen specifically underpins the structural interface between vessels and the parenchymal cells they service.