Light micrograph of respiratory epithelium, cut tangentially. The cells of the epithelium (surface lining) are filled with mucinous substance (pale white-grey to light blue). The individual cells form intersecting polygonal shapes. The deeper layers of the epithelium are not seen in this image, as it has been cut tangentially and parallel to the horizontal plane of the epithelium. Haematoxylin and eosin stained tissue section. Magnification: 400x when printed at 10cm.