Distinguish desmosomes from hemidesmosomes.

• A. Desmosomes anchor epithelial cells to basement membrane; hemidesmosomes connect neighboring cells.
• B. Desmosomes connect adjacent epithelial cells; hemidesmosomes anchor epithelial cells to the basement membrane.
• C. Desmosomes convey electrical signals; hemidesmosomes transport metabolites between cells.
• D. Desmosomes are involved in mucus secretion; hemidesmosomes are involved in hormone signaling.

Answer: (B)

The main idea here is how epithelial cells hold together and attach to the underlying support. Desmosomes are cell–cell adhesions that form strong links between neighboring epithelial cells, giving tissue mechanical strength when it’s stretched. They use cadherin proteins on adjacent cells, connected inside the cell to intermediate filaments, to create a robust junction along the lateral borders.

Hemidesmosomes, by contrast, anchor epithelial cells to the basement membrane. They act like half-desmosomes at the basal surface, using integrins and other linker proteins to attach to laminin in the basement membrane and connect to intermediate filaments inside the cell, securing the cell to the underlying matrix.

So the correct statement reflects that desmosomes connect adjacent cells, while hemidesmosomes attach cells to the basement membrane. The other options describe functions not associated with these junctions (electrical signals, metabolite transport, mucus secretion, or hormone signaling).