What is the function of the basement membrane?

• A. It anchors epithelium to connective tissue and serves as a selective barrier.
• B. It anchors epithelium to connective tissue, provides structural support, and acts as a selective barrier.
• C. It provides blood supply to epithelial tissues.
• D. It generates mucus for luminal surfaces.

Answer: (B)

The basement membrane provides three key roles for epithelial tissues: it anchors the epithelium to the underlying connective tissue, gives structural support, and acts as a selective barrier. Epithelium rests on this thin matrix and stays attached to the stroma through hemidesmosomes, which helps hold the tissue in place. It also serves as a scaffold that supports tissue architecture and guides cell behavior during growth and repair. As a selective barrier, it regulates the movement of molecules between the epithelium and connective tissue, allowing nutrients to diffuse while restricting larger proteins and cells. Its components, including laminin, type IV collagen, and proteoglycans, underlie these functions. The basement membrane does not supply blood to the epithelium (blood comes from the underlying connective tissue), nor does it generate mucus (that comes from secretory cells).