What separates epithelial tissue from underlying tissues?

Epithelial tissue is typically separated from underlying tissues by an extracellular fibrous basement membrane. This membrane acts as a supportive structure, providing attachment for the epithelial cells while also serving as a barrier that helps regulate the passage of molecules and cells between the epithelium and the underlying connective tissue. It helps maintain the structural integrity of the epithelial layer and provides a boundary between different tissue types within the body.