What does the lateral surface refer to in epithelial tissue?

• A. Surface facing the lumen (apical surface)
• B. Surface between cells, between the apical and basal surfaces
• C. Surface in contact with underlying connective tissue (basal surface)
• D. Outer surface that covers tissue (superficial surface)

Answer: (B)

Lateral surfaces are the sides of epithelial cells that contact neighboring cells. Epithelial tissues are polarized, with the apical surface facing the lumen or outside, the basal surface resting on the basement membrane, and the lateral surfaces lying between cells. These lateral surfaces host cell–cell junctions (tight junctions, adherens junctions, desmosomes, etc.) that hold cells together and regulate communication and selective transport between cells, maintaining tissue integrity. So the lateral surface being the surface between cells, between the apical and basal surfaces, is the correct description. The surface facing the lumen is the apical surface, the surface touching the basement membrane is the basal surface, and the term “superficial” is not the specific intercellular side described here.