Immunofluorescent localization of secretin in the canine duodenum

Staining procedures for the endocrine cells of the upper gastrointestinal mucosa: light-electron microscopic correlation for the gastrin-producing cell

Although histochemical, immunohistochemical, and electron microscopic methods have led to the identification of a large variety of endocrine cells in the upper gastrointestinal mucosa, no conventional light microscopic technique capable of the simultaneous identification of these cells has been reported. Such a staining method would be of considerable value to the pathologist as the malfunction of the endocrine cells of the gut, which produce numerous digestive hormones and biogenic amines, is closely related to a number of clinical conditions afflicting man. In this work, after testing three different polychrome staining methods, it has been concluded that a slightly modified Herlant's tetrachrome in tissues fixed in Zenker-formol is the procedure of choice. This method allows the distinction of several different cell types in the upper gastrointestinal mucosa of man and dog and permits the easy identification of the gastrin-producing cells on a routine basis. This identification has been confirmed in the case of two patients with gastrin cell hyperplasia, seen by both light and electron microscopy. Herlant's tetrachrome has proven valuable in the screening of human as well as experimental gastrointestinal tissues and it has been found to be very suitable for recognizing gastrin-producing cell hyperplasias. The usefulness of this method is expected to increase with the establishment of further correlations between the light and electron microscopy of the endocrine cells of the gut.

Cellular localization of gastric inhibitory polypeptide in the duodenum and jejunum

Indirect immunofluorescence studies using an antiserum to purified porcine gastric inhibitory polypeptide indicate, in the gastrointestinal tract of dog and man, that this polypeptide is present in cells situated predominantly in the mid-zone of the glands in the duodenum and, to a lesser extent, in the jejunum. Absolute correlation of the gastric inhibitory polypeptide cell with one or other of the known endocrine-like cells identified by electron microscopy awaits confirmation by electron immunocytochemistry. It is here identified as an endocrine polypeptide cell of the APUD series and, provisionally, as the D(1) cell. While the hormonal status of a given polypeptide depends ultimately on physiological experiments the present results strengthen the view that gastric inhibitory polypeptide is indeed a hormone.