The esophagus is a relatively simple tube which is well adapted to fulfil its function of transporting material from the mouth to the stomach. The elasticity of the mucosa and musculature allows for extension of the lumen during the passage of a bolus of food, and a coordinated nerve plexus and musculature enables peristaltic waves of contraction and relaxation to propel the contents of the lumen to the stomach. On the other hand, the esophagus is one of the first organs to encounter toxic and carcinogenic chemicals in the diet, and the fact that esophageal cancer is one of the cancers with the highest incidence world-wide (Parkin et al. 1988) implies that biochemical defence mechanisms are not sufficiently well developed to protect man against this hazard. While the structure and physiology of the esophagus have been studied in some detail, the biochemistry has been almost completely neglected.

Structure of the normal esophagus

The esophagus is comprised of a straight muscular tube running from the pharynx to the stomach. In the neck region it lies dorsal to the larynx and to the anterior end of the trachea, but in the thorax it is slightly to the left of the trachea. After piercing the diaphragm, the esophagus enters the stomach in the middle of the lesser curvature. It therefore lies mainly in the thorax. The length of the esophagus obviously varies very much with the species of animal. In man it is about 25 cm long, in the rat 5 cm.