Collagen —— forms the main pa of anchoring fibrils in epithelial tissues
**Core Concept**
Collagen is a primary structural protein found in the extracellular matrix, responsible for providing strength and elasticity to tissues. In epithelial tissues, collagen plays a crucial role in anchoring the epithelial basement membrane to the underlying connective tissue.
**Why the Correct Answer is Right**
Anchoring fibrils are composed of collagen VII, which is secreted by basal epithelial cells and forms a complex with laminin-332 to anchor the basement membrane to the underlying dermal tissue. This interaction is essential for maintaining epithelial integrity and preventing blistering diseases. Collagen VII is the primary component of anchoring fibrils, which are critical for the structural stability of epithelial tissues.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because collagen I is a major component of bone, skin, and connective tissue, but it is not the primary component of anchoring fibrils.
**Option B:** This option is incorrect because laminin-332 is a component of the basement membrane, but it is not the primary component of anchoring fibrils.
**Option C:** This option is incorrect because fibronectin is an adhesive glycoprotein that plays a role in cell adhesion and migration, but it is not the primary component of anchoring fibrils.
**Clinical Pearl / High-Yield Fact**
It is essential to recognize the importance of collagen VII in anchoring fibrils, as mutations in the COL7A1 gene can lead to dystrophic epidermolysis bullosa (DEB), a rare genetic disorder characterized by skin fragility and blistering.
**Correct Answer:** C. Collagen VII forms the main part of anchoring fibrils in epithelial tissues.