As the first major section of the gastrointestinal tract, the esophagus encounters food that has only undergone minimal previous digestive processing via mastication and exposure to saliva. It must, therefore, be able to withstand exposure to rough or coarse material like potato chips, broccoli, or even small bits of bone without significant damage. The interior of the upper part of the esophagus is lined with stratified squamous epithelial cells, which heal quickly and are resistant to abrasion and heat. The lower portion of the tube, however, is lined with columnar cells.

The rat esophagus tissue section illustrated in the digital image above was stained with Texas Red conjugated to wheat germ agglutinin, a plant-derived lectin that targets the Golgi apparatus, as well as Alexa Fluor 488 conjugated to phalloidin for cytoskeletal actin. Nuclei were labeled with Hoechst 33342. Images were recorded in grayscale with a 12-bit digital camera coupled to a Nikon Eclipse 80i microscope equipped with bandpass emission fluorescence filter optical blocks. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.