A tissue is a group of similar cells working together to carry out a specific function.Epithelial tissue are layers of cells that line the inner surface of organs.Some epithelial tissue is flat, thin squamous epithelium, such as those which line the blood vessels and alveoli. These are adapted for efficient diffusion as they provide a short diffusion path.They also line blood vessels to give a smooth, frictionless layer.Ciliated epithelia waft substances along. The ciliated cells lining the oviduct move the egg along the oviduct.The ciliated epithelia lining the trachea and bronchioles in the lungs waft mucus containing trapped particles and bacteria up to the back of the throat to be swallowed. The stomach acid then kills the bacteria.Examples of tissues in plants are xylem and phloem.