Most people experience heartburn occasionally during their lifetimes, usually with no long-term ill effects. Heartburn that occurs regularly over a long period of time or that is unusually severe, which is characteristic of gastroesophageal reflux disease (GERD), can be very detrimental, however. Without treatment, the esophagus may be chronically irritated in such patients and may lead to a condition known as Barrett’s esophagus. The squamous cells that normally line the esophagus undergo permanent change in individuals with Barrett’s esophagus, becoming specialized columnar cells. These Barrett’s cells continue abnormal development in some patients and may become cancerous.

The rat esophagus tissue section illustrated in the digital image above was labeled with wheat germ agglutinin (WGA) conjugated to Oregon Green 488. WGA, which selectively binds to N-acetylglucosamine and N-acetylneuraminic (sialic acid) residues, is well suited for staining the Golgi network in fixed cells and tissues since a number of proteins and lipids found in the Golgi apparatus are glycosylated. The specimen was also labeled with Alexa Fluor 568 conjugated to phalloidin (targeting filamentous actin) and Hoechst 33342 (targeting DNA in the nucleus). 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.