What does epithelial tissue depend on for nourishment?

Epithelial tissue relies on nearby capillaries for nourishment because it does not contain blood vessels within its structure. This type of tissue is avascular, meaning it lacks a direct blood supply. Instead, epithelial cells obtain essential nutrients and oxygen through diffusion from adjacent capillaries located in the underlying connective tissue. The thinness of the epithelial layer facilitates this process, allowing the tissue to receive the necessary substances for maintenance and function. The presence of capillaries ensures that the cells can remain viable and responsive, despite their lack of direct vascularization. This characteristic is vital for the role that epithelial tissues play in covering surfaces, lining cavities, and forming glands throughout the body.