Parietal cells

Parietal cells, also known as oxyntic cells, are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and in the cardia of the stomach. They are among the most highly differentiated of the epithelial cells and are of central importance in the study of gastroenterology.

Function

Parietal cells have two major roles. Firstly, they produce gastric acid, an important component of gastric juice, which is used in the stomach to break down the proteins in food. The acid is produced via the proton pump, a process that involves the active transport of hydrogen ions into the stomach.

Secondly, parietal cells produce intrinsic factor, a glycoprotein necessary for the absorption of vitamin B12 in the small intestine. Without intrinsic factor, vitamin B12 cannot be absorbed, leading to a type of vitamin B12 deficiency known as pernicious anemia.

Structure

Parietal cells are large and have a round shape. They are characterized by extensive eosinophilic cytoplasm and a centrally located nucleus. The cytoplasm contains large numbers of mitochondria, reflecting the high energy requirements for acid production.

Clinical significance

Abnormalities in parietal cell function can lead to a number of clinical conditions. Overproduction of gastric acid can result in peptic ulcer disease, while underproduction can lead to hypochlorhydria or achlorhydria. Autoimmune destruction of parietal cells is a major cause of pernicious anemia.

See also

• Gastric acid
• Gastric glands
• Gastroenterology
• Intrinsic factor
• Peptic ulcer disease
• Pernicious anemia