This thin plastic section shows the nonkeratinizing stratified squamous
epithelium that lines and protects the lumen of the esophagus. The epithelium
is composed of multiple layers of cells. Those at the free surface are flattened,
squamous cells, making this a squamous epithelium, although the cells in the
deepest layers are cuboidal and columnar. The presence of flattened nuclei
in cells at the free surface indicates that the cells are alive and not keratinized.
