Dear student,
Epithelial tissues forms the outermost covering of the body, body cavity, and internal organs. They are found in the surface cells of skin, buccal cavity, blood vessels, alveoli, and kidney tubules. Cells are arranged as tightly- packed continuous sheets, without any intercellular space. It separates different organ systems in the body. Thus their location on the surface subjects to lot of damage from environmental surroundings. If the cells are not compactly packed they may not divide rapidly so to replace damaged surface cells and thus won't be able to protect the the cell.
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