Cytologic observations on the pancreatic islets with reference to some endocrine-like cells of the gastrointestinal mucosa

Giemsa stain applied to deplasticized sections to identify pancreatic islet cells

A new application of the Giemsa stain to demonstrate endocrine cells in deplasticized sections of Epon embedded material is described. Its application to the pancreas of Rana temporaria is illustrated. The technique does not require postfixation with OsO4 and is easily performed in 30 min. It allows the easy identification of three types of endocrine cells (A, B, and D). A cells, preferentially located at the islet periphery, stain purple-blue. B cells, which occupy the interior of the islet, display a lilac color. D cells give a strong purple color; they are located both in the periphery of the islets and scattered among acinar cells. Positive identification of the cell types was made by immunocytochemistry and electron microscopy.

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.

Serotonin, noradrenaline, dopamine metabolites in transcendental meditation-technique

The highly significant increase of 5-HIAA (5-hydroxyindole-3-acetic acid) in Transcendental Meditation technique suggests systemic serotonin as "rest and fulfillment hormone" of deactivation-relaxation. Furthermore 5-HT (5-hydroxytryptamine, serotonin) is considered to be the EC-cell (enterochromaffine-cell) hormone requested by Fujita and Kobayashi and its role for EEG synchronisation via area postrema chemoreceptor as anti arousal agent is being discussed. The significant decrease of the catecholamine metabolite VMA (vanillic-mandelic acid) in meditators, that is associated with a reciprocal increase of 5-HIAA supports as a feedback necessity the "rest and fulfillment response" versus "fight and flight". As the adreno medullary tissue serves for hormonal reinforcement of orthosympathetic activity, the Enterochromaffine Cell System (having taken the form of distinct organs in some species as octopus and discoglossus) is suggested to serve via serotonin for humoral reinforcement of parasympathetic activity in deep relaxation.

Aldehyde-fuchsin staining of antral endocrine cells

Correlative studies have been made to identify the endocrine cells stained by Aldehyde-Fuchsin (AF) in the cat and human antral mucosa. D-cells weakly stained by AF after oxidation: this staining might be related to the disulphide group present in the molecule of Somatostatin (the hypothalamic hormone recently localized in D-cells). The gastrin-producing G-cells were on the contrary strongly stained (without oxidation) in tissues fixed in Helly-fluid. Histochemical investigations on the mechanism of such staining lead to the conclusion that it might be related to affinity of the stain for hidden acidic groups.

Identification of glucagon-producing cells (A cells) in dog gastric mucosa

An immunocytochemical technique using specific antiglucagon serum reveals the presence of glucagon-containing cells situated exclusively in the oxyntic glandular mucosa of the dog stomach. Electron microscope examination of the mucosa demonstrated endocrine cells containing secretory granules with a round dense core surrounded by a clear halo, indistinguishable from secretory granules of pancreatic A cells. Like the alpha granules of pancreatic A cells, the granules of these gastric endocrine cells exhibited a peripheral distribution of silver grains after Grimelius silver staining. Moreover, the granules of these cells were found to be specifically labeled with reaction product, using the peroxidase immunocytochemical technique at the ultrastructural level. Accordingly, these cells were named gastric A cells. These data suggest that the gastric oxyntic mucosa contains cells indistinguishable cytologically, cytochemically, and immunocytochemically from pancreatic A cells. It is believed that gastric A cells are responsible for the secretion of the gastric glucagon.

Cytochemical and ultrastructural differentiation of enteroglucagon and pancreatic-type glucagon cells of the gastrointestinal tract

Coordinated studies have been carried out on the glucagon immunoreactive cells of the mammalian gastrointestinal tract (man, dog, rat), using electron microscopy, silver staining and immunocytochemistry. Parallel ultrastructural and immunocytochemical studies have been made with the semithin-thin serial section technique. The results indicate that while the glucagon cells of the oxyntic portion of the stomach are virtually indistinguishable from those of the pancreatic islets (A cells) those of the intestine (EG cells) are completely different. Proper identification of glucagon immunoreactive cells requires the application of morphological and silver staining techniques, at the ultrastructural level.

The ultrastructure of the cell types in the endocrine pancreas of the horse

The islets of Langerhans of the equine pancreas were examined with the electron microscope after immersion or perfusion fixation. Five cell types could be distinguished after fixation by either technique: 1. A-cells, situated at the center of the islets, 2. B-cells, containing mostly "pale granules" and constituting the principal cell type of the periphery of the islets, 3. D-cells, also located mainly at the periphery of the islets, 4. G-cells, found at the edge of the islets and in the exocrine pancreas, and 5. S-cells, (small granule cells), which are relatively few in number and occur only in the islets. The function and age-dependent modifications of these cells are discussed. The formation of light and dark cells and of "mixed cells" are regarded as artifact, since cells of this type occur only under the condition of immersion fixation.

Human gastrin response to secretin after vagotomy

The gastrin response to a liquid meal with and without secretin infusion was studied in nine patients undergoing selective or truncal vagotomy with pyloroplasty for duodenal ulcer disease. Fasting gastrin levels were significantly increased in eight of nine patients after vagotomy, but secretin infusion did not consistently suppress these basal gastrin levels either pre- or postoperatively. Infusion of secretin did significantly lower the integrated gastrin response to feeding both pre- and postoperatively in eight of nine patients. Vagotomy alone did not significantly alter the integrated gastrin response to feeding. This data gives evidence that secretin infusion remains a helpful diagnostic test, differentiating those patients with recurrent ulcer and elevated gastrin levels postvagotomy from those patients with occult Zollinger-Ellison syndrome.

Storage granules of thyroid C cells in the dog: a cytochemical and ultrastructural study, in relation to the masked metachromasia reaction

Masked metachromasia can be demonstrated in thyroid C cells, and other cells of the APUD series, by staining with a metachromatic basic dye after hydrolysis of suitably fixed tissue. The reaction is thought to be due to the presence of polypeptides with a high concentration of side-chain acidic groups. Since most APUD cells possess storage granules, presumed to contain a polypeptide hormone, it has been assumed that the masked metachromasia reaction gives information concerning the contents of these granules. However, there has been an increasing suspicion that the reaction might actually be due to the membrane bounding these granules, rather than to the contents. We have examined, cytochemically and ultrastructurally, dog thyroid tissue which has been subjected to fixation and hydrolysis as in the usual method for masked metachromasia. We found that the membrane surrounding the C cell granules is removed by hydrolysis, confirming the hypothesis that the reaction is due to the contents (hormone and/or matrix)rather than to the membrane. Tissues were fixed in an aqueous mixture containing glutaraldehyde (6 25% v/v), picric acid (three-quarters saturation) and sodium acetate (I% W/V)adjusted to PH 7 with sodium hydroxide. This was found to be a very satisfactory fixative for electron microscopy Some morphological details of C cells were noted, such as the richness of desmosomes between C cells in this species, and frequent direct contact with the colloid.

Genetic aspects of the Z-E syndrome: prospective studies in two kindred; antral gastrin cell hyperplasia

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Electron microscope radioautographic identification of serotonin-synthesizing cells in the mouse gastric mucosa

This study correlates the fine structure of mouse gastric endocrine cells with their ability to synthesize serotonin (5-HT) from 5-hydroxytryptophan (5-HTP). Mice were sacrificed 2 hr after the intravenous injection of 5-HTP-(3)H or 5-HT-(3)H. Their stomachs were processed for light- and electron microscope radioautography in a manner which retained labeled 5-HT while washing out other labeled substances. Stomachs from additional mice were incubated in vitro with 5-HT-(3)H and processed similarly. All morphologic types of mouse gastric endocrine cells exhibited a similar facility to incorporate exogenous 5-HTP and to convert it to 5-HT which was bound intracellularly. Differences in densities of silver grains observed over endocrine cells suggested that individual endocrine cells indeed varied in their ability to synthesize and/or to bind 5-HT; such variations, however, were not reflected by differences in fine structure, with the exception that endocrine cells with few granules always contained little newly synthesized 5-HT. The newly synthesized 5-HT was associated with the intracellular granules. The gastric endocrine cells were not labeled by exogenous 5-HT-(3)H, whereas mast cells were labeled by either 5-HT-(3)H or 5-HTP-(3)H administration. The findings of the present study support the position that the gastric endocrine cells represent a single cell type, at least in respect to serotonin metabolism-that the argyrophil or argentaffin reactivity of these cells merely reflects their amine content at a given time.

The endocrine cells in the epithelium of the gastrointestinal mucosa of the rat. An electron microscope study

The authors of this study examine the question of whether the so-called enterochromaffin or argentaffin cells of the gastrointestinal tract should be considered as a single cell type. The systematic application of purely morphologic methods has led to the conclusion that the epithelium of the gastrointestinal mucosa comprises endocrine cells of several types. This conclusion is primarily based on the uneven and characteristic distribution of the various cell types along the intestinal tract, an observation precluding the interpretation that the different types correspond to diverse functional stages of the same cell. A specific endocrine function may be attributed to each of the given cell types recognized so far on account of their appearance and their localization in characteristic areas of the gastrointestinal tract. It is acknowledged, however, that a purely morphological study leaves room for doubt. The first cell type is probably responsible for the formation of 5-hydroxytryptamine. Cells of type II are morphologically comparable to the pancreatic A cells and may, therefore, be called intestinal A cells. Cell type III comprises intestinal D cells since their appearance corresponds to that of pancreatic D cells. Cell type IV might well be responsible for catecholamine production, whereas gastrin is in all probability produced in endocrine cell type V. As yet, the thorough morphological study of the gastrointestinal epithelium does not provide information as to additional distinct cellular sites of production of the several other hormones isolated from different parts of the gut.