Which structure forms the basal extracellular layer supporting epithelial cells?

Which structure forms the basal extracellular layer supporting epithelial cells?

• A. Basal lamina
• B. Goblet cells
• C. Cilia
• D. Microvilli

Answer: (A)

The basal extracellular layer that supports epithelial cells is the basal lamina. This thin sheet lies beneath the epithelium as part of the basement membrane and provides a foundation for adhesion to the underlying connective tissue. It is secreted by epithelial cells and contains components like laminin and type IV collagen that help anchor cells via integrins and hemidesmosomes, while also guiding cell behavior. Goblet cells secrete mucus and sit within the epithelium, cilia are apical hair-like projections for movement, and microvilli are apical surface enlargements for absorption; none of these form the basal layer that supports epithelial tissue.

The basal extracellular layer that supports epithelial cells is the basal lamina. This thin sheet lies beneath the epithelium as part of the basement membrane and provides a foundation for adhesion to the underlying connective tissue. It is secreted by epithelial cells and contains components like laminin and type IV collagen that help anchor cells via integrins and hemidesmosomes, while also guiding cell behavior. Goblet cells secrete mucus and sit within the epithelium, cilia are apical hair-like projections for movement, and microvilli are apical surface enlargements for absorption; none of these form the basal layer that supports epithelial tissue.