Another cause of reduced secretion of intrinsic factor fects to the parietal cells to inhibit HCl secretion. The facand subsequent pernicious anemia is the loss of gastric tor that mediates the interaction between the connective epithelium in partial or total gastrectomy. Loss of functional tissue cells and the epithelial cells has not been elucidated. gastric epithelium also occurs in chronic or recurrent pep-Recent evidence, however, suggests that most common tic ulcer disease (PUD). Often, even healed ulcerated re-peptic ulcers (95%) are actually caused by a chronic infecgions produce insufficient intrinsic factor. Repeated loss of tion of the gastric mucosa by the bacterium Helicobacter epithelium and consequent scarring of the gastric mucosa pylori. Lipopolysaccharide antigens are expressed on its can significantly reduce the amount of functional mucosa. surface that mimic those on human gastric epithelial cells.
Histamine H2 receptor–antagonist drugs such as The mimicry appears to cause an initial immunologic tolerranitidine (Zantac) and cimetidine (Tagamet), which block ance to the pathogen by the host immune system, thus help-attachment of histamine to its receptors in the gastric mu-ing to enhance the infection and ultimately causing the cosa, suppress both acid and intrinsic factor production production of antibodies. These antibodies against H. pylori and have been used extensively in the treatment of peptic bind to the gastric mucosa and cause damage to the mu-ulcers. These drugs prevent further mucosal erosion and cosal cells. Treatment includes antibiotic eradication of the promote healing of the previously eroded surface. How-bacteria. These treatments for ulcerative disease have made ever, long-term use can cause vitamin B12 deficiency. the common surgical interventions of the past infrequent.
Mucous neck cells are localized in the neck region of the gland and are interspersed with parietal cells.
As the name implies, the mucous neck cells are located in the neck region of the fundic gland. Parietal cells are usually interspersed between groups of these cells. The mucous neck cell is much shorter than the surface mucous cell and contains considerably less mucinogen in the apical cytoplasm. Consequently, these cells do not exhibit a prominent mucous cup. Also, the nucleus tends to be spherical compared with the more prominent, elongated nucleus of the surface mucous cell.
The mucous neck cells secrete a soluble mucus compared with the insoluble or cloudy mucus produced by the surface mucous cell. Release of mucinogen granules is induced by vagal stimulation; thus, secretion from these cells does not occur in the resting stomach.
Chief cells are located in the deeper part of the fundic glands.
Chief cells are typical protein-secreting cells (Fig. 17.9 and Plate 57, page 612). The abundant rER in the basal cytoplasm gives this part of the cell a basophilic appearance, whereas the apical cytoplasm is eosinophilic owing to the presence of the secretory vesicles, also called zymogen granules because they contain enzyme precursors. The basophilia, in particular, allows easy identification of these cells in H&E sections. The eosinophilia may be faint or absent when the secretory vesicles are not adequately preserved. Chief cells secrete pepsinogen and a weak lipase. On contact with the acid gastric juice, pepsinogen is converted to pepsin, a proteolytic enzyme.
Parietal cells secrete HCl and intrinsic factor.