Foveolar cells are mucus-producing cells which cover the inside of the stomach, protecting it from the corrosive nature of gastric acid. Foveolar cells are also known as surface mucous cells or mucous neck cells,[a] depending on the location. These cells line the gastric mucosa and gastric pits. The mucous secreting cells of the stomach can be distinguished histologically from the intestinal goblet cells.
The mucus produced by these cells is extremely important, as it prevents the stomach digesting itself.Parietal cells produce potent hydrochloric acid, which damages cells. Gastric chief cells produce pepsinogen, which is activated by the acid to form pepsin. Pepsin is a protease that can digest and damage stomach cells. To prevent these disastrous effects, mucus and bicarbonate ions (HCO3-) are secreted by the foveolar cells.
The mucus allows the acid at pH above 4 to penetrate lining, but below pH 4 (i.e. when acid is more concentrated) the acid cannot penetrate the mucus. This is called viscous fingering. Thus the foveolar cells can pump out a lot of acid, but acid once in the lumen of the stomach is prevented from returning.