scholarly journals THE ENDOCRINE CELLS IN THE EPITHELIUM OF THE GASTROINTESTINAL MUCOSA OF THE RAT

1969 ◽  
Vol 40 (3) ◽  
pp. 692-715 ◽  
Author(s):  
W. G. Forssmann ◽  
L. Orci ◽  
R. Pictet ◽  
A. E. Renold ◽  
C. Rouiller
Keyword(s):  
Gastrointestinal Tract ◽  
Morphological Study ◽  
Endocrine Cells ◽  
Cell Types ◽  
Endocrine Function ◽  
Cell Type ◽  
Gastrointestinal Mucosa ◽  
Type Iv ◽  
A Cells ◽  
D Cells

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.

The effect of pancreatic mesenchyme on the differentiation of endocrine cells from gastric endoderm

Development ◽  
1987 ◽  
Vol 100 (4) ◽  
pp. 661-671 ◽  
Author(s):  
B. Kramer ◽  
A. Andrew ◽  
B.B. Rawdon ◽  
P. Becker
Keyword(s):  
Endocrine Cell ◽  
Endocrine Cells ◽  
Cell Types ◽  
The Other ◽  
Chick Embryos ◽  
Cell Type ◽  
Pancreatic Insulin ◽  
Somatostatin Cells ◽  
Regional Specificity ◽  
Gut Endocrine Cells

To determine whether mesenchyme plays a part in the differentiation of gut endocrine cells, proventricular endoderm from 4- to 5-day chick or quail embryos was associated with mesenchyme from the dorsal pancreatic bud of chick embryos of the same age. The combinations were grown on the chorioallantoic membranes of host chick embryos until they reached a total incubation age of 21 days. Proventricular or pancreatic endoderm of the appropriate age and species reassociated with its own mesenchyme provided the controls. Morphogenesis in the experimental grafts corresponded closely to that in proventricular controls, i.e. the pancreatic mesenchyme supported the development of proventricular glands from proventricular endoderm. Insulin, glucagon and somatostatin cells and cells with pancreatic polypeptide-like immunoreactivity differentiated in the pancreatic controls. The latter three endocrine cell types, together with neurotensin and bombesin/gastrin-releasing polypeptide (GRP) cells, developed in proventricular controls and experimental grafts. The proportions of the major types common to proventriculus and pancreas (somatostatin and glucagon cells) were in general similar when experimental grafts were compared with proventricular controls but different when experimental and pancreatic control grafts were compared. Hence pancreatic mesenchyme did not materially affect the proportions of these three cell types in experimental grafts, induced no specific pancreatic (insulin) cell type and allowed the differentiation of the characteristic proventricular endocrine cell types, neurotensin and bombesin/GRP cells. However, an important finding was a significant reduction in the proportion of bombesin/GRP cells, attributable in part to a decrease in their number and in part to an increase in the numbers of endocrine cells of the other types. This indicates that mesenchyme may well play a part in determining the regional specificity of populations of gut endocrine cells.

Patterns of calcium localization in pancreatic endocrine cells

1976 ◽  
Vol 21 (1) ◽  
pp. 107-117
Author(s):  
M. Ravazzola ◽  
F. Malaisse-Lagae ◽  
M. Amherdt ◽  
A. Perrelet ◽  
W.J. Malaisse ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
Endocrine Cells ◽  
Secretory Granules ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Calcium Localization ◽  
A Cells ◽  
D Cells

Subcellular calcium localization in the dndocrine cells of rat pancreas was studied by the pyroantimonate precipitation technique. Calcium-containing electron-dense deposits in the endocrine cells were mostly found within secretory granules and along the plasma membrane, but their pattern of distribution in A-, B- and D-cells displayed qualitative and quantitative differences. In B-cells, numerous secretory granules contained deposits located in the halo surrounding the granule core. In A-cells, only few granules contained precipitates in their halo, whereas in D-cells, deposits were situated in the dense core of the secretory granules. Deposits along the plasma membrane occurred generally on the outer leaflet of the plasma membrane of B- and D-cells and on the inner leaflet of that of A-cells. In islets incubated at a high glucose concentration or in the presence of the calcium ionophore A23187, the number of beta granules containing precipitates was significantly increased. By contrast, only few deposits were observed in B-cells incubated in calcium-deprived medium enriched with EGTA. These findings indicate that: the pattern of calcium localization varies in different islet cell types; in B-cells the secretory granules represent one of the major stores of intracellular calcium; and that this store undergoes changes in conditions which alter insulin release.

Fine structure and immunocytochemistry of cells within the endocrine pancreas of the gar (Lepisosteus osseus)

1998 ◽  
Vol 76 (1) ◽  
pp. 6-18 ◽  
Author(s):  
Karen E Groff ◽  
John H Youson
Keyword(s):  
Endocrine Pancreas ◽  
Cell Types ◽  
Structural Features ◽  
Nerve Terminals ◽  
Cell Type ◽  
Similar Morphology ◽  
Islet Tissue ◽  
Ancient Lineage ◽  
D Cell ◽  
D Cells

Routine electron microscopy and immunocytochemistry were used to describe the cell types in the islets of the endocrine pancreas of the gar Lepisosteus osseus, an actinopterygian fish of the order Semionotiformes, which has an ancient lineage. The general fine-structural features of cells composing the islets reflect their synthesis and packaging of protein for liberation at their perivascular surface. Cells are directly apposed to numerous capillaries and they are richly innervated with nerve terminals containing dense-cored vesicles. The islet tissue comprises many B cells, which are easily distinguished by their ubiquitous granules with polymorphous matrix cores and a loose-fitting membrane. These granules are only immunoreactive with an insulin antiserum. Only one type of D cell is found throughout the islets and it contains many granules of varying electron density, the most abundant granule profile being dumbbell-shaped. All granules in this cell type have a tight-fitting limiting membrane and they immunostain with antisomatostatin-14 and -34. Cells at the periphery of the islet contained granules of similar morphology to those in the D cells, but the granules were less numerous. Many granules in the cells were immunoreactive with both antiglucagon and antineuropeptideY, while others immunostained with only one of these antibodies. Since no cells stained exclusively for either glucagon or neuropeptide Y, it was concluded that there are only three cell types in the endocrine pancreas of the gar: B and D cells and a third cell type (A/F) that co-localizes peptides of the glucagon and pancreatic polypeptide family. Although this co-localization is not uncommon in the vertebrate endocrine pancreas, it may have some phylogenetic and (or) ontogenetic significance in this organism.

scholarly journals Yeast alpha 2 repressor positions nucleosomes in TRP1/ARS1 chromatin.

1990 ◽  
Vol 10 (5) ◽  
pp. 2247-2260 ◽  
Author(s):  
S Y Roth ◽  
A Dean ◽  
R T Simpson
Keyword(s):  
Binding Site ◽  
Mating Type ◽  
Chromatin Structure ◽  
Nucleosome Position ◽  
Cell Types ◽  
Alpha Cells ◽  
Cell Type ◽  
Yeast Plasmid ◽  
A Cells ◽  
Cell Type Specific

The yeast alpha 2 repressor suppresses expression of a-mating-type-specific genes in haploid alpha and diploid a/alpha cell types. We inserted the alpha 2-binding site into the multicopy TRP1/ARS1 yeast plasmid and examined the effects of alpha 2 on the chromatin structure of the derivative plasmids in alpha cells, and a/alpha cells. Whereas no effect on nucleosome position was observed in a cells, nucleosomes were precisely and stably positioned over sequences flanking the alpha 2 operator in alpha and a/alpha cells. In addition, when the alpha 2 operator was located upstream of the TRP1 gene, an extended array of positioned nucleosomes was formed in alpha cells and a/alpha cells, with formation of a nucleosome not present in a cells, and TRP1 mRNA production was substantially reduced. These data indicate that alpha 2 causes a positioning of nucleosomes over sequences proximal to its operator in TRP1/ARS1 chromatin and suggest that changes in chromatin structure may be related to alpha 2 repression of cell-type-specific genes.

Yeast alpha 2 repressor positions nucleosomes in TRP1/ARS1 chromatin

1990 ◽  
Vol 10 (5) ◽  
pp. 2247-2260
Author(s):  
S Y Roth ◽  
A Dean ◽  
R T Simpson
Keyword(s):  
Binding Site ◽  
Mating Type ◽  
Chromatin Structure ◽  
Nucleosome Position ◽  
Cell Types ◽  
Alpha Cells ◽  
Cell Type ◽  
Yeast Plasmid ◽  
A Cells ◽  
Cell Type Specific

The yeast alpha 2 repressor suppresses expression of a-mating-type-specific genes in haploid alpha and diploid a/alpha cell types. We inserted the alpha 2-binding site into the multicopy TRP1/ARS1 yeast plasmid and examined the effects of alpha 2 on the chromatin structure of the derivative plasmids in alpha cells, and a/alpha cells. Whereas no effect on nucleosome position was observed in a cells, nucleosomes were precisely and stably positioned over sequences flanking the alpha 2 operator in alpha and a/alpha cells. In addition, when the alpha 2 operator was located upstream of the TRP1 gene, an extended array of positioned nucleosomes was formed in alpha cells and a/alpha cells, with formation of a nucleosome not present in a cells, and TRP1 mRNA production was substantially reduced. These data indicate that alpha 2 causes a positioning of nucleosomes over sequences proximal to its operator in TRP1/ARS1 chromatin and suggest that changes in chromatin structure may be related to alpha 2 repression of cell-type-specific genes.

Somatostatinoma

2011 ◽  
pp. 929-931
Author(s):  
John A.H. Wass
Keyword(s):  
Amino Acid ◽  
Gastrointestinal Tract ◽  
Somatostatin Receptors ◽  
Cell Types ◽  
Enteric Neurons ◽  
Exocrine Function ◽  
Amino Acid Peptide ◽  
Pancreatic Exocrine ◽  
D Cells ◽  
Somatostatin 14

Somatostatin was isolated in 1973 by Paul Brazeau in Roger Guillemin’s laboratory. It was found to have a widespread distribution, not only in the hypothalamus and brain but also in the gastrointestinal tract. Sixty-five per cent of the body’s somatostatin is in the gut, mostly in the D cells of the gastric and intestinal epithelium. It is also present in the myometric and submucosal plexuses. The highest concentration is in the antrum of the stomach and there is a gradual decrease of concentrations down the gastrointestinal tract. Five per cent of the body’s somatostatin is in the pancreas. Infused somatostatin, which has a short half-life of 3 min, has a large number of actions on the pituitary gland, the endocrine and exocrine pancreas, gastrointestinal tract, other hormones, and on the nervous system (Box 6.8.1). Among its various actions of importance in the gastrointestinal tract is the inhibition of gastrin and cholecystokinin (CCK). In the pancreas, insulin and glucagon are inhibited. Nonendocrine actions include inhibition of gastric acid secretion, pancreatic exocrine function, gall bladder contraction, and intestinal motility. Intestinal absorption of nutrients, including glucose, triglycerides, and amino acids, is also inhibited (1). Somatostatin exists in two main forms, as a 14-amino acid peptide (somatostatin 14) present mainly in the pancreas and the stomach, and as a 28-amino acid peptide present mainly in the intestine. Somatostatin 14 is the peptide present in enteric neurons. Somatostatin receptors are present on many cell types, including the parietal cells of the stomach, G cells, D cells themselves, and cells of the exocrine and endocrine pancreas. A large number of tumours also have somatostatin receptors and these include pituitary adenomas, endocrine pancreatic tumours, carcinoid tumours, paragangliomas, phaeochromocytomas, small cell lung carcinomas, lymphomas, and meningiomas. Five different somatostatin receptors (SSTRs) have been cloned (SSTR1–SSTR5) and all are on different chromosomes. These have a varying affinity for somatostatin 14 and somatostatin 28 and a varying tissue distribution with SSTR2 and 5 being predominant in the pituitary (2). Somatostatin can act either as an endocrine hormone or in a paracrine or autocrine way. It probably also has luminal effects in the gastrointestinal tract. Lastly, it can act as a neurotransmitter (3).

Morphological study of the gut in Sagitta setosa, S. serratodentata and S. pacifica (Chaetognatha). Functional implications in digestive processes

1999 ◽  
Vol 79 (6) ◽  
pp. 1097-1109 ◽  
Author(s):  
Y. Perez ◽  
J. Arnaud ◽  
M. Brunet ◽  
J.-P. Casanova ◽  
J. Mazza
Keyword(s):  
Intestinal Epithelium ◽  
Morphological Study ◽  
Secretory Cell ◽  
Secretory Granules ◽  
Ciliated Cell ◽  
Posterior Part ◽  
Cell Types ◽  
Cell Type ◽  
Distinct Cell ◽  
Functional Implications

The study of the digestive epithelium in Sagitta setosa, S. serratodentata, and S. pacifica revealed only a few morphological and cytological differences among the three species. The gut was divided in two main regions. The first is the cephalic region where the epithelium is composed of three distinct cell types (S1, S2, and S3), the ultrastructure of which is probably specialized either for the synthesis of mucosubstances (S1), or enzymes (S3), or both (S2). The second region of the gut extends to the trunk and is mainly composed of the intestine and a short vertical rectum. No intestinal diverticula were observed. The intestinal epithelium displayed two ciliated cell types, anteriorly, a secretory cell type (S4) containing large mucus-like granules, and a second cell type (A) predominated in the posterior part of the intestine. A-cells appear to have two main functions. Although they exhibit secretory granules, they also display typical endocytotic features in their upper half, i.e. coated vesicles, a well-developed tubulo–vesicular network and two distinct types of digestive vacuoles corresponding to an endosome–lysosome-like system. From the distribution and presumed function of the cells, the gut may be divided in two main functional units, i.e. the cephalic and trunk units.

scholarly journals Non-Ca2+-homeostatic functions of the extracellular Ca2+-sensing receptor (CaR) in endocrine tissues

2000 ◽  
Vol 165 (2) ◽  
pp. 173-177 ◽  
Author(s):  
PE Squires
Keyword(s):  
Endocrine Cells ◽  
Cell Function ◽  
Cell Types ◽  
Endocrine Function ◽  
Culture Cells ◽  
Short Commentary ◽  
Endocrine Tissues

The extracellular Ca(2+)-sensing receptor (CaR) links changes in the concentration of extracellular Ca(2+) to changes in cell function. For cells involved in the control of systemic Ca(2+) concentration, this provides an efficient receptor-mediated mechanism to rapidly counteract slight fluctuations in the circulating concentration of Ca(2+). However, all cells that express the CaR are not necessarily involved in Ca(2+) homeostasis. The recent localisation of CaR expression on a variety of cell types more usually associated with non-Ca(2+)-homeostatic endocrine function may have serious repercussions for the interpretation of data in those systems which routinely culture cells under standard hypercalcaemic conditions. This short commentary considers the literature surrounding the identification of the CaR and the potential effects of its localisation on endocrine cells not directly involved in the control of systemic Ca(2+ )homeostasis.

MORPHOLOGY OF ENDOCRINE CELLS IN THE ISLET TISSUE OF THE COD GADUS CALLARIAS

1970 ◽  
Vol 63 (4) ◽  
pp. 679-695 ◽  
Author(s):  
N. W. Thomas
Keyword(s):  
Endocrine Cells ◽  
Secretory Granules ◽  
Cell Types ◽  
Differential Staining ◽  
Cell Type ◽  
Central Mass ◽  
Islet Tissue ◽  
History Of ◽  
Alpha Beta ◽  
Delta Cells

ABSTRACT The principal islet of the cod consists of a central mass of endocrine tissue, surrounded by a capsule of exocrine tissue. Four cell types are recognisable by differential staining and electron microscopy. Three of these correspond in staining reactions and general morphology to alpha, beta and delta cells of other species. Each cell-type contains characteristic secretory granules. The fourth cell-type does not appear to correspond to any other pancreatic endocrine cell although its granules show features common to both alpha and beta cells. It may represent a phase in the life history of one of these cell types or more probably a separate cell-type.

scholarly journals Pheromones and pheromone receptors are the primary determinants of mating specificity in the yeast Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 463-476 ◽  
Author(s):  
A Bender ◽  
G F Sprague
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Types ◽  
Haploid Cell ◽  
Wild Type ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
A Cells ◽  
Alpha Factor ◽  
A Cell ◽  
Specific Proteins

Abstract Saccharomyces cerevisiae has two haploid cell types, a and alpha, each of which produces a unique set of proteins that participate in the mating process. We sought to determine the minimum set of proteins that must be expressed to allow mating and to confer specificity. We show that the capacity to synthesize alpha-factor pheromone and a-factor receptor is sufficient to allow mating by mat alpha 1 mutants, mutants that normally do not express any alpha- or a-specific products. Likewise, the capacity to synthesize a-factor receptor and alpha-factor pheromone is sufficient to allow a ste2 ste6 mutants, which do not produce the normal a cell pheromone and receptor, to mate with wild-type a cells. Thus, the a-factor receptor and alpha-factor pheromone constitute the minimum set of alpha-specific proteins that must be produced to allow mating as an alpha cell. Further evidence that the pheromones and pheromone receptors are important determinants of mating specificity comes from studies with mat alpha 2 mutants, cells that simultaneously express both pheromones and both receptors. We created a series of strains that express different combinations of pheromones and receptors in a mat alpha 2 background. These constructions reveal that mat alpha 2 mutants can be made to mate as either a cells or as alpha cells by causing them to express only the pheromone and receptor set appropriate for a particular cell type. Moreover, these studies show that the inability of mat alpha 2 mutants to respond to either pheromone is a consequence of two phenomena: adaptation to an autocrine response to the pheromones they secrete and interference with response to alpha factor by the a-factor receptor.

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