Gastric folds

The gastric folds (or gastric rugae) are coiled sections of tissue that exist in the mucosal and submucosal layers of the stomach. They provide elasticity by allowing the stomach to expand when a bolus enters it. These folds stretch outward through the action of mechanoreceptors, which respond to the increase in pressure. This allows the stomach to expand, therefore increasing the volume of the stomach without increasing pressure. They also provide the stomach with an increased surface area for nutrient absorption during digestion. Gastric folds may be seen during esophagogastroduodenoscopy or in radiological studies.

Layers
The gastric folds consist of two layers:
 * Mucosal layer – This layer releases stomach acid. It is the innermost layer of the stomach. It is affected by the hormone histamine, which signals it to release hydrochloric acid (HCl).


 * Sub-mucosal layer – This layer consists of different vessels and nerves, ganglion neurons, and adipose tissue. It is the second layer of the stomach and supports the mucosa.

Clinical significance
Thickening of the gastric folds may be observed by endoscopy or radiography and may aid in the differential diagnosis of many disease processes including:
 * Gastritis
 * The folds become very thick due to inflammation.


 * Peptic ulcer disease
 * Ulcers cause breaks in the mucosa and cause erosion of the sub-mucosa.


 * Zollinger-Ellison syndrome
 * Gastrin levels increase due to tumors, which cause an increase in the gastric fold size.


 * Ménétrier's disease
 * The mucosa pits are in excess causing thickening of the folds.


 * Carcinoma
 * Helicobacter pylori infection
 * Causes inflammation of the folds.


 * Gastric syphilis
 * Cytomegalovirus
 * Mucosa change shape causing rugae enlargement.


 * Sarcoidosis
 * Causes thickening of the folds.