Endocrine cells of the human gastric mucosa

Multiple Gastric Carcinoids and Pernicious Anemia: Report of a Case

A case of pernicious anemia associated with multiple gastric carcinoids is reported. The neoplastic growth was composed of enterochromaffin-like (ECL) cells, and ECL cell hyperplasia was observed also in hyperplastic polyps, inside the fundic glands and in small nests lying in the lamina propria (microcarcinoidosis). The possible relation between pernicious anemia and ECL cell hyperplasia is discussed.

Neuroendocrine pathology of the stomach: the Parma contribution

The current knowledge on gastric neuroendocrine pathology essentially developed in the last four decades. The historical evolution of the concepts and of the relevant clinical implications is described from the perspective of a group actively participating in this research domain. The histamine-producing enterochromaffin-like (ECL) cells have been recognized as the leading cell type involved in the most significant alterations of gastric neuroendocrine cells. The trophic stimulus exerted by circulating gastrin has been demonstrated to have a crucial role on proliferative changes of ECL cells through a sequence of hyperplasia-dysplasia-neoplasia described by Solcia et al. (Digestion 41:185-200,1988). The development of ECL cell tumors in rats treated with toxicological doses of inhibitors of gastric acid secretion prompted appropriate anatomoclinical investigations proving the lack of tumor risk in humans when therapeutic dosages of the drugs are used. Moving from the comprehensive concept of gastric carcinoid, different types of neuroendocrine tumors have been identified in the stomach with substantial variations in prognosis and treatment options. In general, ECL cell tumors developed in hypergastrinemic conditions were found to behave better than those originating outside the setting of hormonal stimulation. Pathological features highly predictive of patient survival have been described. The genetic changes involved in tumor development and progression have revealed substantial overlapping with those of neuroendocrine tumors of other foregut derivatives (i.e., pancreas, duodenum, lung) delineating a family of neuroendocrine tumors genetically distinct from those of the distal parts of the digestive system.

Neuroendocrine proliferations of the stomach: a pragmatic approach for the perplexed pathologist

The classifications of neuroendocrine proliferations that lead from enterochromaffin-like cell hyperplasia to neuroendocrine tumors in the stomach are complicated and relatively inaccessible to nonspecialists. Consequently, these lesions tend to remain widely underdiagnosed until they progress to easily recognizable neuroendocrine tumors. This review provides simple, yet rigorous guidelines on how to recognize, classify, and diagnose the neuroendocrine proliferations found in the stomach, emphasizing the most common background in which they arise, atrophic gastritis. After a succinct outline of the types and distribution of the neuroendocrine cells in the normal gastric mucosa we discuss the most common situations in which the pathologist needs to think about gastric neuroendocrine cells. In general practice gastric biopsy specimens are often numerically and topographically inadequate for the evaluation of atrophic gastritis; therefore, we have included an algorithm to address specifically the steps that should be taken when confronted with suboptimal sampling. Finally, we illustrate the suggested diagnostic process with 4 cases that are fairly representative of the type of situations encountered in everyday practice. The pathologist who follows our simple steps will be better aware of this neglected area of gastric pathology and will learn to suspect, recognize, and accurately diagnose the most common abnormalities of the neuroendocrine system in the stomach.

Methods in neuroendocrine histopathology, a methodological overview

Light microscopy is still the main tool in diagnostic histopathology, though it does not always lead to a definitive diagnosis. It has therefore been a constant ambition to develop methods which can add further information to the diagnosis. In endocrine pathology, a major problem has been to distinguish between neuroendocrine and non-neuroendocrine tumours. The silver stains, such as the Bodian, Grimelius and Sevier-Munger methods, were the first useful "general neuroendocrine" markers. Electron microscopy can also be useful for identifying neuroendocrine tumours. A further step forward was the introduction of histochemical fluorescence methods, as these could identify biogenic amines. With the introduction of immunohistochemical techniques, tumours could be characterized in a more specific way regarding peptide hormones and biogenic amines content, proliferation factors, hormone receptors, etc. Another method, DNA cytometry, has been used mainly in predicting the prognosis. In situ hybridization can be a useful complement to the histopathological diagnosis when other methods have failed to demonstrate the neuroendocrine nature of the tumour. Some endocrine tumours, especially the well-differentiated ones, still cause diagnostic problems in predicting tumour behaviour, why further complementary methods would be of great value.

Cell proliferation in pathogenesis of esophagogastric lesions in pigs

Esophagogastric ulcer is an independent disease in swine that is characterized by ulcerous autodigestion of the cutaneous mucosa, which does not exhibit a tendency to recover, but, on the contrary, a tendency toward severe hemorrhaging, with a predominantly lethal outcome. Since it develops in the part of the stomach that is morphologically and functionally different from other glandular mucosa, it was questioned earlier whether it could be a peptic ulcer based on its nature. Spontaneous ulcers, usually of the stomach, commonly occur in many domestic animals. Some of these lesions are chronic and they may occur in either the glandular or squamous-lined regions of the stomach. As with the human disease, the pathogenesis in domestic animals is multifactorial, poorly understood, and variable between and within species. Environmental stress and dietary factors are very important in the ulcer disease in swine. It has been shown that the Helicobacter spp. is strongly associated with naturally occurring ulcer and preulcer lesions of the pars esophagea in swine, which raises the possibility that Helicobacter spp. is an important factor in the pathogenesis of these lesions. The dynamics of the development of esophagogastric ulcers imply hyperplastic lesions (parakeratosis and hyperkeratosis), keratolysis, erosions, peptic necrosis, and the development of ulcers with all the characteristics of peptic ulcerations in other localities. In addition, K6 is expressed in association with the mucosal changes. The pattern of the intermediate filaments of keratin suggests that epithelial proliferation, which leads to visible hyperkeratosis, constitutes the essence of gastric ulcers in swine.

Silver stains demonstrating neuroendocrine cells

During the preimmunohistochemical era, silver stains were an important part of the staining arsenal for identifying certain tissue structures and cell types in tissue sections. Some of them were useful for demonstrating endocrine cells, especially in the gastrointestinal tract. Until the late 1950s, silver stains, particularly those identifying endocrine cells, were accompanied by a number of technical difficulties resulting from uncontrolled staining factors. In the 1960s, new silver stains were developed for endocrine cell types and these stains gave reproducible results. One of the "older" silver stains and two of the "newer" ones are emphasized in this presentation, namely the Masson, the Grimelius and the Sevier-Munger techniques. The Masson stain demonstrates the enterochromaffin (EC, serotonin) cells, the Grimelius stain is a broad endocrine cell marker, and the Sevier-Munger technique demonstrates EC and EC-like cells and the C-cells of the thyroid. Especially in the preimmunohistochemical era, these staining methods often were used for histopathological diagnosis, particularly the Grimelius technique. The silver stains were developed empirically, and with few exceptions the chemical background is not known. Staining protocols are included.

Characterization and species differences in gastric ghrelin cells from mice, rats and hamsters

Ghrelin is a newly identified gastric peptide hormone that has various important functions, including growth-hormone release and appetite stimulation. Ghrelin-immunoreactive cells (ghrelin cells) are characterized by X-type endocrine cells in the rat stomach. In the present study, we analysed ghrelin cells in fundi of stomach from ICR mice and Syrian hamsters immunohistochemically, immunoelectron microscopically and morphometrically, and compared the results with those from Wistar rats. Immunohistochemistry revealed that ghrelin cells were sparsely distributed in the proper gastric glands in all species. The number of ghrelin cells per unit area in hamsters was significantly lower than that in rats. Immunoelectron microscopy detected ghrelin immunolabelling in granules in the X-type endocrine cells. However, the diameter of granules in the hamsters was significantly smaller than that in the mice and rats. Gastric ghrelin contents were determined by radioimmunoassay, and levels in the hamsters were significantly lower than those in mice and rats. The results from mice were identical to those from rats. In conclusion, gastric ghrelin cells in mice and hamsters are characterized by X-type endocrine cells, as has been observed in rats. However, the data indicated that gastric ghrelin production was lower in hamster than in mouse or rat.

Immunocytochemical and ultrastructural characterization of endocrine cells in the larval stomach of the frog Rana temporaria tadpoles: a comparison with adult specimens

According to immunostaining and ultrastructural patterns, Rana temporaria tadpole stomach displays a well-differentiated endocrine population comprising, at least, six cellular types: ECL, EC [serotonin], D [somatostatin] - all three of them abundant -, P [bombesin] - less numerous -, CCK-8 [cholecystokinin/gastrin] and A [glucagon/glicentin] - both very scarce. Larval endocrine cells are mainly located in the surface epithelium and show open or closed morphologies. Cellular diversity is similar in tadpoles and frogs, with the exception of immunoreactivity for gastrin-17, found in adults in numerous cells. Larval cells display mature ultrastructural traits, although with smaller secretory granules. The different distribution of endocrine cells, which in adults are preferentially located in the glands, probably refers to different functional requirements. However, the rich vascular plexus present in larval mucosa may be an efficient transport medium of surface hormones to-gastric targets. The enhancement in adults of endocrine population and correlative increase in hormonal secretion indicates a more active functional role, probably related to the shift from herbivorous to carnivorous habits. In summary, the tadpole gastric endocrine population, although not as numerous as that of adult frogs, displays histological traits that indicate a relevant (immunoreactive and ultrastructural properties, cellular diversity) and specific (surface location, relative abundance of open-type cells) role of local regulatory factors in amphibian larval gastric function.

Gastric endocrine cells: types, function and growth

The history of gastric endocrine cells identification and functional characterization is briefly outlined. An up to date classification of such cells is given. Present status of histopathological, histochemical, ultrastructural and molecular investigations on gastric endocrine hyperplasia and neoplasia is summarized and briefly discussed.

Enterochromaffin-like (ECL) cells and their growths: relationships to gastrin, reduced acid secretion and gastritis

ECL cells are argyrophilic endocrine cells of the stomach. Their distribution is species specific, however they are consistently located in the oxyntic mucosa and, in particular, in very close contact with the adenomeres of acidopeptic glands. ECL cells store histamine and are considered a key element in the mechanisms of gastric acid secretion as controlled by gastrin stimulus. Their peculiar anatomical disposition and secretory properties strongly suggest that ECL cells exert their function by a paracrine mechanism, i.e. by releasing histamine in the extracellular spaces surrounding acid-producing parietal cells. ECL cell activity is strongly stimulated by gastrin, which, once applied as a long-standing stimulus, also exerts a potent proliferating effect. Long-lasting hypergastrinaemia has been demonstrated to elicit ECL cell proliferation in laboratory animals, inducing ECL cell hyperplasia, dysplasia and ECL cell tumours, i.e. argyrophilic gastric carcinoids. However, in experimental rodents it is believed that hypergastrinaemia is not per se a stimulus capable of inducing ECL cell transformation, a predisposing genetic background being required for tumour development in endocrine organs. In man, long-standing hypergastrinaemia exerts the same proliferative pressure on ECL cells and is associated with hyperplasia with or without dysplastic changes and carcinoid development. Clinical evidence suggests that other factors, both genetic and environmental, are required to induce ECL cell transformation and carcinoid development. For this reason human gastric argyrophilic ECL carcinoids are subdivided into three main groups depending on their clinical background: (1) gastric carcinoids in patients with chronic atrophic gastritis; (2) gastric carcinoids in patients with Zollinger-Ellison and multiple endocrine neoplasia type 1 syndrome (MEN-ZES); and (3) solitary, sporadic gastric carcinoids. The clinical assessment of carcinoid-bearing patients is strongly recommended for better diagnosis and management of patients.

[Immunohistochemical and ultrastructural study of endocrine cells from the pyloric region of the European mole (Talpa europaea)]

The distribution and the morphology of some endocrine cells (gastrin, somatostatin and 5-HT immunoreactive) in the pyloric region were studied in the Talpa europaea, an insectivore representing one of the most primitive living Eutherians. The immunohistochemical studies enabled us to identify and calculate the percentage of each cell type: the most numerous endocrine cells were gastrin immunoreactive; fairly numerous appeared somatostatin immunopositive; less numerous were 5-HT immunoreactive cells. While the ultrastructural observations let us describe four endocrine cell types: G cells producing gastrin, D cells containing somatostatin, EC cells of the gastric type producing 5-HT and D1 cells whose content is still unknown.

Development of the bovine duodenum with reference to enterochromaffin cells

The present light microscopic study describes the morphological changes which occur in the duodenal mucosa of the bovine fetus from the third month of gestation until birth with regard to the sequence of appearance and morphology of enterochromaffin cells. The mucosa of the duodenum is prepared for digestive activity during the first months of development. This becomes obvious in the early differentiation of the fetal intestinal mucosa. The enterocytes in villus epithelium contain glycogen in the early months. These glycogen pools seem to shrink during the following months. They may provide a metabolic reserve for the fetus, which derives all of its nutrition from carbohydrates. Enterochromaffin cells appear in the three month old bovine fetus with two cell-types situated in the epithelial lining of crypts and villi. The density of enterochromaffin cells increases during gestation. There were no findings to indicate that the fetal enterochromaffin cells did not originate from endoderm. The early appearance from enterochromaffin cells (which are the producers of serotonin, 5-hydroxytryptamine) correlates with first gastrointestinal movements, which are known to commence in the first third of gestation, leading us to believe that 5-HT represents the chemical inducer of muscular motility in the developing intestine.

Morphology and pathogenesis of endocrine hyperplasias, precarcinoid lesions, and carcinoids arising in chronic atrophic gastritis

The spectrum of endocrine cell changes occurring in 80 cases of body-fundus chronic atrophic gastritis (CAG), mostly type A or multifocal, including various types of hyperplasia, precarcinoid lesions (20 cases), and neoplasia (carcinoid, 24 cases) have been analyzed histologically, histochemically, and ultrastructurally. Changes associated with gland atrophy, pyloric- or intestinal-type metaplasia, regenerative hyperplasia, and hypergastrinemia have been identified and their neoplastic potential evaluated in the light of their proliferative capacity (bromodeoxyuridine incorporation) and clinicopathologic behavior. A close link between disseminated precarcinoid lesions of non-tumor mucosa and multiple carcinoids (carcinoidosis) arising in hypergastrinemic type-A CAG is suggested. Hyperplastic changes, including endocrine cell clusters, seem to have no or only minimal neoplastic potential.

Gastrointestinal carcinoid tumours. Histogenetic, histochemical, immunohistochemical, clinical and therapeutic aspects

The increased knowledge of the pathobiology of gastrointestinal carcinoid (neuroendocrine) tumours and the improved therapeutic possibilities have brought a demand for more precise diagnosis. Although the carcinoid tumours can often be tentatively recognized in routinely processed microscopic slides, their more accurate identification requires additional diagnostic procedures. General neuroendocrine markers such as the argyrophil reaction of Grimelius and immunohistochemistry with application of antibodies against chromogranin A and of neuron-specific enolase are discriminatory staining methods which are used to reveal the neuroendocrine origin of almost all highly differentiated carcinoid tumours of the gastrointestinal tract. Mid-gut carcinoids, which predominate among these tumours almost unexceptionally contain serotonin. This biogenic amine can be demonstrated by the argentaffin reaction of Masson, serotonin immunoreactively or by formalin-induced fluorescence. The characteristic staining pattern of mid-gut carcinoids is almost invariably preserved in the metastatic deposits and consequently the staining methods for identifying serotonin can also be used on metastases to reveal a primary mid-gut carcinoid. The enterochromaffin-like (ECL) cell carcinoids of the body and fundic area of the stomach often seen in association with pernicious anaemia are argyrophil with the Sevier-Munger silver stain. Other neuroendocrine tumours, viz. antral, duodenal and rectal carcinoids should be studied by a battery of relevant peptide hormone antisera for adequate diagnosis. During the last decade new peptide hormones have been found in circulation in patients with carcinoid tumours, but serotonin and urinary 5-HIAA are still the most important markers for carcinoids of the mid-gut origin. Other clinically useful tumour markers are chromogranin A + B, pancreatic polypeptide, human chorionic gonadotropin alpha and beta subunits. For localizing procedures, angiography is the most reliable investigative method for primary tumours in the gut, whereas CT-scan and ultrasound investigations are good for detection of liver metastases. During the last five years, the therapy for malignant carcinoid tumours has been considerably improved. Chemotherapy has only revealed objective response rates in about 10-30% of the patients giving median survivals from start of therapy of about 10 months. Recently treatment with alpha interferons and the new somatostatin analogue octreotide have given objective responses in 50-75% of patients with malignant mid-gut carcinoid tumours. These patients have now a median survival from start of therapy of 70 months when treated with alpha interferons. In the future new therapies will come into use such as monoclonal antibodies and perhaps also agents blocking different growth factors.

Endocrine cells in the human oxyntic mucosa. A histochemical study

The oxyntic mucosa of the human stomach harbors at least five different endocrine cell types (ECL cells, A-like or X cells, somatostatin cells (D), enterochromaffin (EC) cells, and D1 or P cells). Little is known about their functional roles, and of the hormones they produce only somatostatin has been identified. The relative frequency and regional distribution of the different endocrine cell populations were studied in 13 adults with no manifest gastrointestinal disease. From each of them at least three biopsy specimens were taken at seven fixed locations within the oxyntic mucosa. The specimens were examined for the different endocrine cell types by means of immunocytochemistry (staining with antisera against chromogranin A,5-hydroxytryptamine, and somatostatin) and silver staining techniques (demonstration of argyrophil cells by the methods of Grimelius or Sevier-Munger). Chromogranin-positive cells included all endocrine cells identified by the other staining techniques. Grimelius-positive cells included all endocrine cells except the somatostatin cells. Sevier-Munger-positive cells, finally, included the ECL cells and the EC cells. The frequency of ECL cells could be calculated by subtracting the number of EC cells from the number of Sevier-Munger-positive cells. The ECL cells represented 35% of the total endocrine number, somatostatin cells 26%, and EC cells 25%. The remaining 14% consisted of A-like cells, D1 cells, and P cells. Generally, the endocrine cells predominated in the basal portion of the glands, but the various populations of endocrine cells were not uniformly distributed in the various regions of the oxyntic mucosa. However, representative specimens could be obtained from the main body of the stomach, and the results indicate that the examination of a fairly small number of specimens from the main body of the stomach may be sufficient for assessing the frequency of endocrine cells in the oxyntic mucosa of individual patients.

The endocrine cells in the gut of Mugil saliens Risso, 1810 (Teleostei): an immunocytochemical and ultrastructural study

The endocrine cells in the gut of Mugil saliens Risso, 1810 (leaping grey mullet) were investigated by immunocytochemical and electron microscopic techniques. Gastrin-, glucagon-, and somatostatin-immunoreactive cells were identified in the cardiac and cecal stomach regions, located mainly in the lower part of the gastric folds and in the upper part of the glands. Substance P-, somatostatin-, and pancreatic polypeptide (PP)-immunoreactive cells were found between epithelial cells in the pyloric stomach region. Gastrin-, cholecystokinin (CCK)-, gastric inhibitory polypeptide (GIP)-, substance P-, Met-enkephalin- and PP-immunoreactive cells were observed throughout the intestine while only the last three of these appeared in the posterior intestine. Nine types of gastroenteroendocrine cells were ultrastructurally characterized; some of them were related to the cell types immunocytochemically identified.

Endocrine pancreas of Testudo graeca L. (Chelonia) in summer and winter: an immunocytochemical and ultrastructural study

Insulin-, glucagon-, somatostatin-, and PP-immunoreactive cells were identified immunocytochemically using antisera raised against mammalian hormones in the pancreas of Testudo graeca in both winter and summer. The endocrine cells were present throughout the gland, forming scarce islets except in the splenic region. The insulin cell islets were larger and more numerous in the splenic region than in the duodenal one. Winter glucagon-immunoreactive cells were found mainly in isolation while the summer ones occurred in groups which showed no immunoreactive central area; in both seasons these cells were more numerous in the splenic region than in the duodenal one. Somatostatin-immunoreactive cells were found isolated or grouped together more frequently in the splenic region in the summer specimens. No PP-immunoreactive cells were found in the splenic region, although they were numerous and isolated in the duodenal zone. Four cell types (B, A, D, and PP cells) were ultrastructurally characterized by the shape, size, and electron density of their respective secretory granules. Certain ultrastructural differences were detected in the summer and winter endocrine pancreatic cells. In summer specimens a fifth cellular type was observed. The presence of B, D, and PP cells among the epithelial pancreatic duct cells may confirm the comparatively primitive organization of the T. graeca endocrine pancreas.

Serotonin-storing cells of the chicken duodenum: light, fluorescence and electron microscopy, and immunohistochemistry

In an attempt to identify duodenal endocrine cells emitting formaldehyde-induced fluorescence (FIF), chicken duodena were studied by combined fluorescence, ultrastructural, silver impregnation and immunohistochemical methods in the same or consecutive sections. Our results show that: (1) Almost all the cells emitting yellow fluorescence by both the Falck-Hillarp and the Furness methods exhibit an immunohistochemical reaction with serotonin (5-HT) antiserum. (2) Almost all cells radiating yellow fluorescence by the Furness method stain with toluidine blue in Epon-embedded sections, but, by high-voltage electron microscopy, can be subdivided into two types of cell containing either small round or polymorphous types of granules. (3) In the sections from which resin had been removed, all the cells emitting yellow FIF show argentaffinity by the Singh method, but not all cells display argyrophilia with the Grimelius method. (4) Cells exhibiting both argyrophil and argentaffin reactions in deresined serial sections are also separated into two types of cell, containing either small spherical or polymorphous types of granules by conventional electron microscopy in thin sections. Therefore, chicken enterochromaffin cells emit yellow FIF, store 5-HT, show both argentaffinity and argyrophilia, but are ultrastructurally classified into two types of granule-containing cells which may be related to polypeptides coexisting with 5-HT.

Ultrastructural characterization of fundic endocrine cell hyperplasia associated with atrophic gastritis and hypergastrinaemia

Clinical and experimental evidence indicates that carcinoid tumours of the stomach fundic mucosa represent another example of hormone-dependent neoplasm, gastrin being the hormone involved in tumour induction. In this context hyperplasia of fundic endocrine cells associated with chronic atrophic gastritis (CAG) and hypergastrinaemia is regarded as the most frequent preneoplastic lesion. However, the cell type involved in this hyperplasia has not been clarified. To elucidate this problem fundic endocrine cells were characterized ultrastructurally in 9 patients from which endoscopic gastric biopsies were obtained. ECL cells were the most frequent cell type in 8 cases, in 4 of which they were more numerous than all other cell types taken together. D1 cells were the most frequent type in one case while they were inconspicuous in the other cases. P cells were found with a frequency in each case intermediate between that of ECL cells and that of D1 cells. These results indicate that fundic endocrine cell hyperplasia occurring in hypergastrinaemic CAG is in most cases cytologically similar to that found in other hypergastrinemic conditions, in which the gastrin-dependent ECL cells were already found to prevail. They also explain why fundic carcinoids arising in CAG are mostly composed of ECL cells. The relation between ECL, D1 and P cells, if any, remains obscure.

Alterações quantitativas das células neuroendócrinas no Megacólon chagásico

Utilizando-se técnicas histoquímicas pela prata (Masson-Fontana e Sevier- Munger) estudaram-se a distribuição e o número de células enterocromafins (EC) e do conjunto EC mais células argirófilas (ARG) em peças cirúrgicas de megassigmóide chagásico. Observou-se que tanto nos "megas"(n = 16) como nos controles (n = 8), a posição das células EC e ARG na mucosa foi predominantemente basal, com distribuição irregular, principalmente das EC. A análise histológica revelou aparente aumento numérico das EC e do conjunto EC mais ARG. Todavia, contagens sistematizadas mostraram que somente o conjunto dessas células apresentou aumento estatisticamente significativo (P < 0,01). Realizou-se também o estudo morfométrico da mucosa e das musculares que revelou espessamento significativo (P

Neuron-specific enolase in mucosal endocrine cells and carcinoid tumours of the small intestine: a comparative study with neuron-specific enolase immunocytochemistry and silver stains

Endocrine cells of human small intestinal mucosa, small intestinal carcinoids and carcinoid liver metastases were stained with an immunocytochemical technique using an antiserum against neuron-specific enolase (NSE), with the argyrophil technique of Grimelius and with the argentaffin technique of Masson. In the normal mucosa, scattered NSE-immunoreactive cells were seen mainly in the deeper parts of the crypts. These cells, as shown in the same sections, corresponded to the argentaffin and/or argyrophil cells indicating that they were of endocrine type. All intestinal carcinoids (16 cases) displayed NSE immunoreactivity. However, this reaction did not correlate on the cellular level with the silver techniques employed. Thus, many tumour cells were NSE immunoreactive but lacked an argentaffin or argyrophil reaction and vice versa. On the light microscopical level the silver techniques reveal the presence of neurohormonal granules in the tumour cells, while the NSE immunoreactivity appears to disclose neuroendocrine differentiation of the tumour cells irrespective of their hormone and granular content. Out of 13 carcinoid liver metastases, eight displayed strong NSE immunoreactivity, three were weakly stained and two were unreactive. Consecutive or the same tumour sections showed an argentaffin and argyrophil reaction in all carcinoid metastases. Since silver staining provides one type of information and NSE immunocytochemistry another, they provide in combination a good discriminator for neuroendocrine tumours.

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.

Localization of histamine and histamine H2-receptor antagonists in the gastric mucosa

Histamine stimulates acid secretion by the parietal cell and this secretion is inhibited by the histamine H2-receptor antagonists. Whole body autoradiography showed that radioactivity from 14C-histamine was localized in the artery walls of the stomach and in the muscularis mucosae, but that the level in the fundic mucosa was the same as the blood. When the H2-receptor antagonists burimamide, metiamide and cimetidine were labelled with 35S, 14C or 3H and dosed to rats, whole body autoradiography showed that the stomach was predominantly labelled in the glandular mucosa from 5 to 120 min after administration. Microautoradiography in the rat and dog after intravenous injection of [3H]metiamide or [3H]cimetidine demonstrated an uptake of tritium in the parietal cell cytoplasm that was 3- to 4-times greater than that found in adjacent peptic cells or areas of muscularis mucosa. The preferential labelling persisted at a low level up to 6h after injection in the rat. The localization of radioactivity from the H2-antagonists in the parietal cell cytoplasm correlates well with their pharmacological activity in preventing acid secretion from this cell.

Gastric carcinoids of argyrophil ECL cells

Histochemical and ultrastructural studies were carried out in four gastric carcinoids, two of which were associated with atrophic gastritis and pernicious anemia. All tumors showed intense argyrophilia and vesicular granules resembling those of endocrine enterochromaffinlike (ECL) cells in normal human gastric mucosa. Tumor cells were found to be unreactive to all the 18 available antiserums to gut hormones, including gastrin, somatostatin, glucagon, and pancreatic polypeptides. The tumors were interpreted as ECL cell argyrophil carcinoids with the various degrees of differentiation and atypia.

Immunocytochemical study of argyrophil (Sevier Munger) endocrine cells of adult human pancreas

Bouin-fixed tissues from non-diabetic adult human pancreata display an argyrophil reaction mainly in the periphery of the islets with the silver technique of Sevier-Munger. The nature of these argyrophil cells was examined after restaining by an indirect immunocytochemical method using antibodies against insulin, glucagon, somatostatin and pancreatic polypeptide. After this procedure the argyrophil cells were identified as glucagon (A-) cells and pancreatic polypeptide (PP-) cells, although the latter exhibited a weaker reaction. The insulin (B-) cells and somatostatin (D-) cells were unreactive. The results show that the Seiver-Munger stain is of equal value to the Grimelius silver nitrate stain in adult human pancreatic islets after fixation in Bouin's fluid.

Bombesin-like immunoreactivity in the avian gut and its localisation to a distinct cell type

The distribution of a bombesin-like immunoreactive peptide in the avian gastro-intestinal tract was analysed by combined radioimmunoassay and immunocytochemistry. Radioimmunoassay of tissue extracts showed that the largest quantities of bombesin-like immunoreactivity were present in the proventriculus (64.5 +/- 6.0 pmol/g) with smaller but still considerable amounts in the gizzard (40.0 +/- 6.0 pmol/g). Immunocytochemically the extractable bombesin-like immunoreactivity was localised in numerous endocrine cells. These, in the proventriculus, were found mainly in the deeper layers of the mucosa. Further study of these cells by the semi-thin/thin technique revealed the presence of characteristic secretory granules. The functional name BN is proposed for this cell type.

The vagal release of 5-hydroxytryptamine from enterochromaffin cells in the cat

Enterochromaffin cells (EC) from the cat duodenum were studied before and after electrical efferent stimulation of the cervical vagi by means of electron microscopy and fluorescence histochemistry according to the Hillarp-Falck technique. From the same animals portal blood plasma was assayed for serotonin (5-HT) at various stages of the nerve stimulation. Within 15 min after the onset of vagal nerve stimulation there was a more than twofold increase of the portal 5-HT levels, which returned to normal after cessation of stimulation. There was also a pronounced reduction in the fluorescence intensity of EC demonstrating a lowered intracellular 5-HT level. Ultrastructurally there was evidence for basal exocytosis as well as for a release of osmiophilic material from the EC directly into the gut lumen after nerve stimulation. Together, these observations strongly suggest a vagally induced 5-HT release from EC in the cat.

Morphological observations on the normal human cardiac glands

The majority of human cardiac glands that lie immediately distal to the termination of esophageal epithelium are compound or branched tubular glands. They empty into overlying gastric pits. The glands of this region are often organized into lobule-like complexes by the surrounding connective tissue of the lamina propria. The secretory tubules contain mucous cells, parietal cells and endocrine cells. The mucous cell is the most common cell type observed and appears to comprise two populations. The majority are pyramidal in shape and show numerous spherical, electron-dense secretory granules. Profiles of rough endoplasmic reticulum are observed scattered throughout the cytoplasm and Golgi complexes occupy a supranuclear position in relation to forming secretory granules. Morphologically this cell type appears similar to the mucous neck cell of the fundus. Secretory granules of a second mucous cell type are mottled in appearance and show an area of increased electron density near the limiting membrane. Parietal cells are observed and appear identical to those in the fundus. The large number of endocrine cells present raises questions concerning the traditional concept of the function of these particular glands.

A gastrin releasing peptide from the porcine nonantral gastric tissue

This paper presents evidence for the existence in extracts from porcine non-antral gastric tissue of a peptide capable of causing substantial rises of plasma immunoreactive gastrin levels in a dose dependent manner and of stimulation of gastric acid and pepsin secretion. Obtained data show that the peptide is basic and that its gastrin releasing properties are at least partially resistant to atropinisation and beta-receptor blockade. Antrectomy almost eliminates the rise in plasma IRGa when the peptide is administered. The possible relationship of this peptide to amphibian bombesin is discussed.

Multiple endocrine cell types in thyroid medullary carcinoma. Evidence for calcitonin, somatostatin, ACTH, 5HT and small granule cells

10 cases of thyroid medullary carcinoma (TMC) have been studied ultrastructurally and histochemically. Well differentiated calcitonin-producing C cells were present in all tumours, being prevalent in 9 cases. 5-Hydroxytryptamine (5HT) storing cells were found in two cases, somatostatin immunoreactive cells in at least 5 cases and ACTH-immunoreactive cells in 4 cases. Ultrastructurally, at least 3 types of apparently non-C cells were observed. Type 1 cells with large, poorly osmiophilic granules resembling those of gastroenteropancreatic D cells, were present in 6 cases; they appeared to correlate well with somatostatin immunoreactive cells. Type 2 cells with large osmiophilic granules were found in 5 cases; they resembled ACTH-MSH cells of the human pituitary and may correspond to the ACTH-immunoreactive cells of light microscopy. Type 3 cells with small granules and an unknown function were found in 6 cases, always in scarce number. It is concluded that TMC, although mainly made up of C cells, usually contains large proportions of other endocrine cell types.

Tritiated thymidine autoradiographic study on the origin and renewal of argentaffin cells in the pyloric gland of hamsters

The origin and renewal of the argentaffin cells in the pyloric glands of hamsters were studied by flash, cumulative and pulse labelling autoradiography with 3H-thymidine. The argentaffin cells were identified by the Diazo Method using Fast Red B Salt. By flash labelling autoradiography, it was shown that the argentaffin cells located from the middle to the lower level of the pyloric mucosa were not labelled with 3H-thymidine, indicating that this cell type has no proliferative activity. On the 10th and the 20th day of cumulative labelling, 31% and 63% of the argentaffin cells in the gland were found to be labelled, respectively. The labelled argentaffin cells were concentrated in the upper part of the gland (around the region of the isthmus), and no label was found over nuclei of the cells at the lowermost level of the gland. These labelled cells were shown to undergo a downward migration in the days following pulse labelling. They were replaced by unlabelled (and weakly or very weakly labelled) cells which arose at the region of the isthmus. The argentaffin cells in the pyloric gland are thought to arise from epithelial precursor cells at the region of the isthmus. The labelled argentaffin cells in the gland were found to decrease in number almost exponentially after pulse labelling. This indicates that the life span of argentaffin cells is not fixed, but their renewal conforms to the "random loss system". The half time of turnover of this cell population was 15 days on average.

The endocrine cells of the pancreas and related tumours. Ultrastructural study and classification

Up to seven endocrine cell types have been identified ultrastructurally in the pancreas, including glucagon A cells, insulin B cells, somatostatin D cells, pancreatic peptide F cells and 5-hydroxytryptamine EC cells. In addition, D1 cells, which have been proposed as the cell type producing VIP and possible P cells of unknown function are seen. Various patterns of endocrine cell differentiation have been found in 20 endocrine pancreatic tumours. Well and poorly differentiated B cells have been identified in 6 insulinomas, diagnostic G cells in 3 out of 7 gastrinomas, D1 and/or F cells in 7 diarrheogenic tumours. Moreover, cells apparently unrelated to the prevalent clinical syndrome have been noted in 8 of the 20 tumours. Granular non diagnostic cells (poorly diagnostic gastrin cells? D1 cells?) were particularly frequent in gastrinomas; agranular or poorly granular cells, either by "active" or "Stem cell" type, were present in nearly all tumours, particularly in diarrheogenic tumours, gastrinomas and malignant insulinomas. A cytological classification of pancreatic endocrine tumours is proposed.

The ultrastructure of endocrine cells in the corpus of the stomach of human fetuses

The ultrastructural development of endocrine cells from the corpus of fetal human stomachs is described. Samples were taken from fetuses ranging in fertilization age from 6-8 to 22 weeks. The identifying features used for the classification of the various types of endocrine cells were their basal locations in the epithelium, the presence and morphology of their characteristic granules and the sizes of the mitochondria. Five types of endocrine cells with specific granules were found:D, EC, ECL, AL and D1. The type and number of endocrine cells increased as development proceeded. The endocrine cells were confined to the epithelium, they did not reach the lumen and they appeared to develop in situ. The D, EC and ECL cells were the most numerous. The fetal endocrine cells resembled morphologically those found in the stomachs of various adult animals. The EC, ECL and D1 cells contained small slender mitochondria with few cristae. Intramitochondrial granules were absent in all the cell types. Agranular electron-lucent cells with small mitochondria were considered to be immature endocine cells. The advanced stage of differentiation observed in these cells suggest that they may be capable of producing and storing biogenic amines and polypeptide hormones. Their possible involvement in the synthesis of serotonin, enteroglucagon and intrinsic factor is discussed.

[Development and function of endocrine cells in the proventriculus of the chicken (author's transl)]

An argyrophil endocrine cell type with typical intraepithelial development is seen initially on the 8th day of incubation in the epithelium of the main lumen of the chicken-proventriculus. During the embryonic period, rapid development of these cells can be observed with a quantitative maximum on the 13th day of incubation. At this time increased digestive efficiency is necessary for the chicken embryo with the start of gastric secretion combined with the first swallowing of albumen. There is a subsequent decrease in the number of endocrine cells in the main lumen epithelium, their function in hatched or adult specimens is largely taken over by cells which appear in the epithelium of the glands of the proventriculus on the 16th and later days of incubation. On the 2nd day after hatching the adult distribution pattern of endocrine cells in the proventriculus is attained.

Histologic characteristics of insulinomas and gastrinomas. Value of argyrophilia, metachromasia, immunohistology, and electron microscopy for the identification of gastrointestinal and pancreatic endocrine cells and their tumors

In a first step of our investigation the staining characteristics, especially the argyrophilia and metachromasia, of immunohistologically identified endocrine cells of the pancreatic islets and of the gastroduodenal mucosa were tested. These staining characteristics were then examined on insulinomas and gastrinomas. Contrary to normal B cells which generally react positively with aldehyde fuchsin and pseudoisocyanine but not argyrophilic with the Grimelius method, the neoplastic B cells give inconsistent results with conventional staining methods. Yet neoplastic B cells often show argyrophilic structures. Immunohistologically, most benign insulinomas are rich in insulin-containing cells, whereas in malignant types such cells are rare. The carcinomas, however, show a typical and distinct Grimelius argyrophilia. The tumor cells of gastrinomas are Grimelius argyrophilic and slightly metachromatic, as normal G cells, yet, contrary to A1 cells, they are only exceptionally stainable with the Hellerström method. Despite the great number of Grimelius positive tumor cells, generally only a few reacted with antigastrin serum. Nevertheless, the immunohistology is the most reliable method for the diagnosis of gastrinomas. Electron microscopic results are often difficult to interpret, since gastrinomas, as well as undifferentiated or malignant insulinomas, may predominantly contain atypical secretion granules.

Intestinal endocrine cells of chicks around the time of hatching

The duodenum of 16-day Black Australorp chick embryos, and the duodenum, ileum, large intestine and caeca of 18-day embryos and of chicks within 30 h of hatching, have been studied by electron microscopy. Cells were found with secretory granules resembling those in mammalian EC, S, A-like, EG and D cells (terminology of Solcia et al., 1973), and were on this basis tentatively identified accordingly. The distribution and frequency of the chick cells in different parts of the tract correspond well to the situation in mammals.

Gastric carcinoid following gastrojejunostomy

A carcinoid tumor of the gastric body was found in a patient who had a gastrojejunostomy done for duodenal ulcer 36 years earlier. Association of gastric carcinoid with gastrojejunostomy has previously been described by Lemmer. In contrast, such tumors have never been observed when the more common surgical procedure for peptic ulcer was used, ie, gastric resection. On the basis of recent knowledge on gastric endocrine cells, the authors suggest a relationship between the gastrojejunostomy and the carcinoid tumor, probably related to an elevated gastrin release.

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.