Artery in lung tissue. Digitally enhanced light micrograph of a thin section through lung tissue with haematoxylin and eosin. This view shows an artery (centre left) surrounded by alveoli. At lower right is a bronchiole, lined with ciliated columnar epithelial cells. At top right is cartilage supporting a bronchus, one of the major airways of the lung, keeping it from collapsing. Alveoli are the tiny air sacs of the lungs where gases are exchanged between the air and the blood in the blood vessels.