Which structure forms channels between cells to allow communication?

• A. Gap junctions
• B. Desmosomes
• C. Zonula Occludens
• D. Hemidesmosomes

Answer: (A)

Cells communicate directly with neighboring cells through gap junctions, which form channels that connect the cytoplasm of adjacent cells. These channels are built from connexin proteins that assemble into connexons; when two connexons from neighboring cells align, they create a pore that allows ions and small signaling molecules to pass. This direct exchange enables rapid coordination of cellular activity, such as synchronized heart muscle contraction or coordinated metabolic responses in tissues.

Desmosomes provide strong mechanical adhesion between cells by linking intermediate filaments, not channels for communication. Zonula occludens (tight junctions) seal the space between cells to prevent paracellular leakage and help maintain distinct cell surfaces. Hemidesmosomes attach epithelial cells to the basement membrane, anchoring tissue rather than forming intercellular channels.