Foveolar cells or surface mucous cells are

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

-producing cells which cover the inside of the stomach, protecting it from the corrosive nature of

gastric acid Gastric acid, gastric juice, or stomach acid is a digestive fluid formed within the stomach lining. With a pH between 1 and 3, gastric acid plays a key role in digestion of proteins by activating digestive enzymes, which together break down the ...

. These cells line the

gastric mucosa The gastric mucosa is the mucous membrane layer of the stomach, which contains the glands and the gastric pits. In humans, it is about 1 mm thick, and its surface is smooth, soft, and velvety. It consists of simple columnar epithelium, lamin ...

(mucous neck cells are found in the necks of the gastric pits). The mucus-secreting cells of the stomach can be distinguished histologically from the intestinal

goblet cell Goblet cells are simple columnar epithelial cells that secrete gel-forming mucins, like mucin 5AC. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct, but may use apocrine methods, budding off their secre ...

s, another type of mucus-secreting cell.

Structure

The

that lines the inner wall of the stomach has a set of microscopic features called gastric glands which, depending on the location within the stomach, secrete different substances into the lumen of the organ. The openings of these glands into the stomach are called

gastric pits Gastric pits are indentations in the stomach which denote entrances to 3-5"Secretions from several gastric glands flow into each gastric pit" Principals of Anatomy & Physiology 15th Ed 2017, Gerard Tortora & Bryan Derrickson tubular shaped gastric ...

which foveolar cells line in order to provide a protective alkaline secretion against the corrosive

Microanatomy

Foveolar cells line the surface of the stomach, the gastric pits, and the top part of gastric glands: the neck. They constitute a

simple columnar epithelium Simple columnar epithelium is a single layer of columnar epithelial cells which are tall and slender with oval-shaped nuclei located in the basal region, attached to the basement membrane. In humans, simple columnar epithelium lines most organ ...

, as they form a single layer of cells and are taller than their width. Depending on their location, foveolar cells can be divided in two groups: surface mucous cells, which line the surface and the gastric pits; and mucous neck cells, which are a part of the neck of gastric glands along parietal cells. Surface mucous cells have large quantities of mucin granules in their apical (top) surface and project short

microvilli Microvilli (singular: microvillus) are microscopic cellular membrane protrusions that increase the surface area for diffusion and minimize any increase in volume, and are involved in a wide variety of functions, including absorption, secretion, ...

into the lumen of the stomach. Mucins are large glycoproteins that give the mucus its gel-like properties. As mucins are lost during routine histology preparation, they stain pale, but if preserved correctly the cells stain strongly with special techniques like PAS or toluidine blue, the last representing the

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

ic nature of foveolar cell secretions. Below the mucin granules, surface mucous cells have a

Golgi apparatus The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles ins ...

, the

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucle ...

, and small amounts of rough endoplasmic reticulum. Mucous neck cells are located within gastric glands, interspersed between parietal cells. These are shorter than their surface counterpart and contain lesser quantities of mucin granules in their apical surface.

Function

The mucus produced by these cells is extremely important, as it prevents the stomach from digesting itself.

Parietal cells Parietal cells (also known as oxyntic cells) are epithelial cells in the stomach that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and body regions of the ...

produce potent hydrochloric acid, which damages cells.

Gastric chief cell A gastric chief cell (or peptic cell, or gastric zymogenic cell) is a type of gastric gland cell that releases pepsinogen and gastric lipase. It is the cell responsible for secretion of chymosin in ruminant animals. The cell stains basophilic upo ...

s 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.

Notes

References

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