Secretion of Pepsinogen by the Pyloric Glands of the Dog, With Some Observations on the Histology of the Gastric Mucosa

Abstract

Summary Histologic study of the gastric mucosa of the dog, according to the Marks-Drysdale staining technique, showed an abrupt disappearance of peptic cells marking the boundary between fundic and pyloric glands. Below this boundary the parietal cells became progressively more sparse and showed changes in form and staining reactions, but were still present within a few millimeters of the pyloroduodenal junction. The principal cell type of the pyloric glands, the mucous glandular cells, gave a positive periodic acid-Schiff staining reaction and, in the necks of the glands, showed a transition to mucous neck cells indistinguishable from their counterpart in the fundic glands. Pouches of the pyloric gland area were prepared in 8 dogs. The line of transection of the stomach was 5 cm. or less from the pylorus. Biopsies from this line of transection showed the characteristics described above for the pyloric glands. No peptic cells were seen in sections prepared by the Marks-Drysdale technique or the CambelSgouris modification of the Bowie technique. The juice secreted by these pouches was scant, viscous, and alkaline. It invariably contained a protease active on radioiodina ted serum albumin substrate at pH 2.0. The pH activity curve of pyloric juice was essentially identical with that of crystalline swine pepsin. Exposure of pyloric juice to alkali caused no loss of proteolytic activity unless the juice had first been acidified; the protease of pyloric juice thus behaves, in this regard, like pepsinogen. Crystalline pepsin added to pyloric juice could be fully recovered in terms of proteolytic activity, indicating that a pepsin inhibitor is not present in the juice. Feeding caused a decrease in concentration of proteolytic activity of the juice. Injection of bethanechol produced no significant change in concentration of proteolytic activity.