Non-G cell gastrin-producing tumours of the pancreas

A light and electron microscopic study on the pancreatic ductal system

To investigate morphological features of the human pancreatic ductal system, light and electron microscopic studies were performed, on the comparative basis with those of several species of mammals. The human pancreas possessed relatively well-developed ductal system, as compared with those of other mammals. Furthermore, it had unique centroacinr cells containing numerous mitochondria. The mode of innervation to the ducts, and cytological features such as cilia formation and mucin production were also revealed. Several kinds of endocrine cells including A, B, D1, ECn, presumptive EC1, and presumptive EC2 or K could be identified, but a few remained unclassifiable. The above findings are considered to be prerequisite for understanding the physiology, especially of bicarbonate production, and pathology, especially of oncogenesis of the exocrine and endocrine pancreas.

Pancreatic polypeptide (PP) cells in the PP-rich lobe of the human pancreas are identified ultrastructurally and immunocytochemically as F cells

The ultrastructure of immunohistochemically identified PP cells has been investigated by applying the serial semithin/thin section technique to the human pancreas, with special reference to the posterior part of the head, reputed to originate from the ventral primordium. PP cells of this area differ from those already identified in the rest of the pancreas and correspond to a cell, not yet described in the human pancreas, characterized by larger granules of very variable shape and structure. Such granules resemble those of so-called "F cells", i.e. the PP cells of dog uncinate process and cat duodenal lobe, also coming from the ventral primordium. Thus, human "ventral lobe" PP cells have peculiar potentialities which are expressed in distinctive structural patterns of presently unknown functional meaning.

Ultrastructural and immunohistochemical demonstration of pancreatic polypeptide-containing F-cells in the stomach and pancreas of Tupaia belangeri

The gastro-entero-pancreatic (GEP) system in Tupaia belangeri contains a specific cell which reacts with antisera to pancreatic polypeptide (PP). The cells are scattered between exocrine pancreatic cells and also found in the pancreatic islets. Furthermore, they are also located in the fundic glands and to a very small extent in the corpus mucosa and in the glands of the upper duodenum. The cell reacting with antisera against PP is identified as the F-cell which has a specific ultrastructure especially with respect to its secretion. The present identification of the F-cell as the PP-cell in pancreas and stomach is discussed with respect to its possible functional implications.

Staining of human pituitary glands with lead hematoxylin in comparison with other histochemical procedures, including the immunoenzyme technique

Human pituitary glands and pituitary adenomas, obtained by surgery or at autopsy, have been stained with lead hematoxylin and the results were compared with those of other histochemical procedures, including the immunoperoxidase technique. Lead hematoxylin positivity was found in the cytoplasm of melanocorticotroph, thyrotroph as well as gonadotroph cells, indicating that lead hematoxylin has no selective affinity for melanocorticotroph cells. Lead hematoxylin positive cells also stained with the PAS technique. Lead hematoxylin positivity was not revealed in growth hormone cells or in prolactin cells. Basophilic adenomas, composed of melanocorticotroph cells and associated with Cushing's disease or with Nelson's syndrome or unaccompanied by hormonal hypersecretion, showed intense lead hematoxylin positivity. Thus, no correlation was evident between lead hematoxylin positivity and secretory activity. Acidophilic or chromophobic adenomas consisting of growth hormone cells, prolactin cells, stem cells, undifferentiated cells or oncocytes, however, were negative. It can be concluded that the lead hematoxylin staining techniques a reliable, easy and reproducible histochemical method, and its use can be recommended in studies related to adenohypophysial cytology.

Spontaneous Pancreatic beta cell tumor in the rat. A light and electron microscopic study

Fine structural study of a pancreatic neoplasm found at autopsy of a 27-month-old female Long-Evans rat showed that the tumor consisted of, and derived from beta cells of the islets of Langerhans.

Pancreatic polypeptide - a postulated new hormone: identification of its cellular storage site by light and electron microscopic immunocytochemistry

A peptide, referred to as pancreatic polypeptide (PP), has recently been isolated from the pancreas of chicken and of several mammals. PP is thought to be a pancreatic hormone. By the use of specific antisera we have demonstrated PP immunoreactivity in the pancreas of a number of mammals. The immunoreactivity was localized to a population of endocrine cells, distinct from the A, B and D cells. In most species the PP cells occurred in islets as well as in exocrine parenchyma; they often predominated in the pancreatic portion adjacent to the duodenum. In opossum and dog, PP cells were found also in the gastric mucosa. In opossum, the PP cells displayed formaldehyde - induced fluorescence typical of dopamine, whereas no formaldehyde-induced fluorescence was detected in the PP cells of mouse, rat and guinea pig. Also in these latter species, however, PP cells appear to possess amine-handling properties, a feature common to many peptide hormone-producing cells. The ultrastructure of the PP cells was defined by combining immunohistochemistry of semi-thin plastic sections with electron microscopy of adjacent ultrathin sections. PP cells show the ultrastructural features of peptide hormone-secreting cells. The PP cells of cat and dog contain fairly large, rather electron-lucent granules, and are probably identical with the previously described F cells. The PP cells of rat, guinea-pig, chinchilla and man contain small, fairly electron-dense granules. In these latter species no F cells are found. By immunoperoxidase staining of ultrathin sections, the PP immunoreactivity was found to be localized to the cytoplasmic granules. These observations provide support for the view that PP is a true pancreatic hormone.

On argyrophil reactions of endocrine cells in the human fetal pancreas: a light and electron microscopic study

The endocrine cells in the pancreas of five human fetuses with gestational ages of 18-20 weeks were examined by light and electron microscopy with special regard to argyrophil reactions. B-cells and typical A- and D-cells were easily identified electron microscopically on the basis of their typical secretory granules. In the Grimelius argyrophil silver stain, a concentration of silver grains over the less electron dense peripheral mantle of the A-cell secretory granules was observed by electron microscopy. In the Hellerström and Hellman modification of the argyrophil Davenport alcoholic silver stain, silver grains were concentrated over the internal structures of the D-cell secretory granules. With this stain an accumulation of silver grains was also seen at the surface of the A-cell secretory granules. The argyrophil reaction of the A-granules was less pronounced than in the D-cells. In addition to B-cells and A- and D-cells, two other types of endocrine cell were observed by electron microscopy. These cells were argyrophil with the silver impregnation method of Grimelius. The electron microscopic findings at least partly explain the frequent overlapping between the two staining methods observed at the light microscope level.

Immunohistochemical localization of human pancreatic polypeptide (HPP) to a population of islet cells

HPP is the human counterpart of APP--a polypeptide that has been isolated from avian pancreas and shown to exert pronounced biological effects. The availability of anti-HPP serum enabled us to use immunohistochemical procedures for the localization of HPP in human pancreas. A small population of pancreatic islet cells showed strong immunofluorescence after staining with anti-HPP serum. The HPP cells were mainly localized at the periphery of the islets. Sometimes they were also seen scattered in the exocrine parenchyma as well as within the epithelium of small to medium-sized ducts. While rare in the pancreas of adult man, HPP cells were abundant in certain parts of the pancreas of foetuses (18-20 weeks gestational age). Their staining properties showed them to be distinct from the A, Band D cells of the pancreatic islets.

Pathomorphologic, biochemical, and diagnostic aspects of gastrinomas (Zollinger-Ellison syndrome)

The clinical symptomatology of the Zollinger-Ellison syndrome and the pathologic anatomy of gastrinomas are reviewed. Experience with 17 patients with the Zollinger-Ellison syndrome is presented with special reference to stimulation tests (secretin, glucagon, calcium infusion, test meal) and to localization and immunohistologic, ultrastructural, and biochemical findings in gastrinomas. Multiple hormone production by the tumors is frequent. The ultrastructure and the Sephadex G-50 gel filtration patterns of immunoreactive gastrin in sera and tumors are not uniform and are not related to localization of the tumors in the pancreas or duodenum or to the gastrin concentration. Hyperplasia of the pancreatic islets is a frequent finding in gastrinoma patients, suggesting that hypergastrinemia may stimulate islet growth.