Question

multiple choice question
an extracellular junction that forms an impermeable barrier is called a(n)
tight junction
gap junction
adhesion junction

Explanation:

Tight junctions seal adjacent epithelial cells in a narrow band just beneath their apical surface. They limit the passage of molecules and ions through the space between cells, forming an impermeable barrier. Gap junctions allow for communication between cells by forming channels for small - molecule exchange, and adhesion junctions mainly provide cell - to - cell or cell - to - matrix adhesion, not an impermeable barrier.

Answer:

tight junction