Gastritis. Light micrograph of a section through an inflamed human stomach (gastritis), showing an abnormal accumulation of white blood cells (leucocytes) in the connective tissue deep to the surface mucosal epithelium. The leucocytic infiltration includes neutrophils, lymphocytes, plasma cells and eosinophils that populate the tissue in response to damage caused, for example, by excessive alcohol, certain drugs such as aspirin, stress, autoimmune reactions, or infectious agents notably H. pylori bacteria. Chronic gastritis may lead to peptic ulcers and in some cases gastric cancer. Magnification: x125, when printed 10 centimetres wide.