Histochemical and proliferative changes preceding the onset of spontaneous gastric adenocarcinoma in Mastomys natalensis.

The histochemical and proliferative changes preceding spontaneously developing gastric adenocarcinoma were examined in Mastomys natalensis. The stomachs of 86 inbred animals from the DWZ strain were examined between 1 and 24 months of age. Two thirds of the animals had a small solitary ulcer in the middle of the lesser curvature which was observed by the first month of age. With increasing age, more and more dysplastic glands invading the submucosa were seen around the ulcer and eventually adenocarcinoma was observed after 12 month. Histochemical alterations included increased intracellular peanut lectin and Concanavalin A binding sites in the gastric pits and the development of lectin binding sites and of acid glycoproteins in the surface epithelium. Using 3H thymidine and autoradiography increased labelling and mitotic indices with extension of the progenitor area to the mucosal surface were observed around the ulcer. The coexistence of these histochemical and histokinetic alterations may represent an early sign of malignant potential in the gastric mucosa.