Lung lining. Coloured Scanning Electron Micrograph (SEM) of a section through the internal lining of the human lungs. Also known as bronchial epithelium, this lining helps to keep the lungs free of infection. Clumps of fine hairs, called cilia (blue & green) are seen at top of image. These protrude from the tops of specialised epithelial cells. Oval nuclei of these columnar epithelial cells are seen (brown at lower image). Rhythmic movements of the cilia move bacteria & other particles away from the gas- exchanging parts of the lungs, towards the throat where they can be swallowed or coughed up. Magnification: x1700 at 6x6cm size. Magnification: x1410 at 6x6cm size.