Final answer:
The presence of submucosal glands is an identifying feature of the esophagus. These glands are located in the submucosa, a layer of dense connective tissue underneath the mucosa, and they release digestive secretions.
Step-by-step explanation:
An identifying structural feature of the esophagus is the presence of submucosal glands. The mucosa of the esophagus features a non-keratinized, stratified squamous epithelium to protect against erosion from food particles. The lamina propria within the mucosa contains mucus-secreting glands. Beneath the mucosa, the submucosa consists of a broad layer of dense connective tissue that connects to the muscularis layer and contains submucosal glands which release digestive secretions.
The muscularis layer varies throughout the esophagus: it is made up of skeletal muscle in the upper third, a combination of skeletal and smooth muscle in the middle third, and smooth muscle in the lower third. Unlike the stomach and intestines, which have a serosal layer, the esophagus is covered by a layer of loose connective tissue called the adventitia.