Which junction provides mechanical strength via intermediate filaments?

• A. Tight junctions
• B. Adherens junctions
• C. Desmosomes
• D. Gap junctions

Answer: (C)

Desmosomes provide mechanical strength by anchoring intermediate filaments, like keratin, from one cell to those in neighboring cells. This link forms a sturdy, distributed network that helps tissues resist tearing and shear forces. Transmembrane cadherins (desmogleins and desmocollins) extend between cells to hold them together, while intracellular plaque proteins (such as desmoplakin) connect these cadherins to the intermediate filament cytoskeleton. Because intermediate filaments are designed for tensile resistance, desmosomes are especially important in tissues that experience a lot of stretch, such as the skin and heart.

In contrast, tight junctions seal spaces between cells and regulate permeability; adherens junctions connect cadherins to actin filaments to help maintain tissue structure; and gap junctions form channels for chemical communication between cells. The key point is that desmosomes, linking intermediate filaments across cells, are the structures that confer strong mechanical cohesion.