What are hemidesmosomes and their function?

• A. Anchoring epithelial cells to the basement membrane via integrins.
• B. Forming tight junctions between neighboring cells.
• C. Anchoring cells to neighboring cells through cadherins.
• D. Producing the basal lamina.

Answer: (A)

Hemidesmosomes are specialized attachments that anchor epithelial cells to the underlying basement membrane. They use integrin receptors, especially α6β4, to bind components like laminin in the basal lamina, linking the cell’s intermediate filaments (keratin) inside to the extracellular matrix outside. This creates a strong, stable connection at the cell’s basal surface and helps resist mechanical stresses on epithelial tissues, such as skin and mucosa. It’s different from tight junctions, which seal spaces between neighboring cells, and from desmosomes/adherens, which connect adjacent cells to each other via cadherins. The basal lamina itself is an extracellular matrix layer produced by epithelial and surrounding cells, not something hemidesmosomes produce.