Surface electron microscopical changes of the gastric mucosa in experimental porcine stress ulceration.

Gastric mucosal changes in 8 piglets subjected to a transient hypovolaemic shock were studied using scanning electron microscopy (SEM). The mucosal lesions during the shock were characterized by progressive degenerative changes in the mucous membrane of the stomach. These surface changes included flattening or swelling of the individual cells. The flattening of the mucous membrane was later connected with red cell diapedesis through it. These changes were most typical in the areas of haemorrhagic gastritis and preceded the ulcer formation. Following retransfusion, the affected epithelial lining appeared greatly distended over the oedematous lamina propria, with almost complete loss of structural detail. Masses of red blood cells were seen to emerge through the epithelium as an indication of subepithelial haemorrhage. It is possible that the injured epithelium is actually broken down by the pressure of the underlying mucosal haemorrhage and oedema. At later stages, the ulcerated areas showed complete loss of epithelial cells and thus the underlying structureless lamina propria, covered by necrotic cell remnants, blood cells and fibrin, was denuded.