On the immunocytochemical localization of the vasoactive intestinal polypeptide.

The distribution of vasoactive intestinal polypeptide (VIP) immunoreactive nerves and endocrine cells in the gastrointestinal tract and pancreas of a number of mammalian and submammalian species has been examined in order to throw light on the exact localization of this peptide. Seven out of 8 VIP antisera demonstrated numerous nerve fibers in the gut, whereas one antiserum (TR2) revealed only scattered, few nerve fibers. The distribution of endocrine cells demonstrated by the different VIP antisera varied considerably. Thus, some antisera demonstrated only endocrine cells in the feline antrum, others only colonic endocrine cells and still others only endocrine cells of the upper gut and pancreas. The variability in staining pattern of endocrine cells as well as recent radioimmunological data makes it opportune to suggest that true VIP is a neuronal peptide and that endocrine cells store peptides resembling, but not being identical with, VIP (VIPoids).     

Ontogeny of the endocrine pancreas

The ontogenesis of the endocrine pancreas has been a subject of controversy. The discussion essentially was about organogenesis and histogenesis of islets of Langerhans. Now, the endodermic origin seems well established by several experimental approaches. The variation of the aspects of the islets and of the number of endocrine cells are re-called as well as the functional activity during fetal life. Numerous neuropeptides have been found in endocrine pancreas, so the content of the different endocrine cell types is reviewed with respect to the classic hormones.     

Quantitative characteristics of the endocrine cells of the duodenal glands of Carnivora

In the duodenal glands of the Carnivora investigated endocrine elements have been revealed, a part of them is presented as serotonin-producing EC-cells. Endocrine cells are situated in terminal parts and in glandular ducts, among them elements of open and close types are distinguished. Distribution of these cells in the glandular lobules is subjected to the distal gradient regularity, specific for the gastrointestinal tract mucosal membrane. Amount of endocrinocytes in the glands is much less than in the gut crypts. There is no correlation between distribution of the endocrine cells in the glands and in the crypts. The results of unifactor analysis of variance demonstrate a slight effect of the taxonomic position of the species on the number of endocrine cells in the duodenal glands. The proper endocrine apparatus of the duodenal glands is supposed to produce a local regulatory influence on the secretory activity of exogenic glandulocytes, as well as ensure humoral connections of the duodenal glands with other parts of the gastrointestinal tract.     

Notch signaling differentially regulates the cell fate of early endocrine precursor cells and their maturing descendants in the mouse pancreas and intestine

Notch signaling inhibits differentiation of endocrine cells in the pancreas and intestine. In a number of cases, the observed inhibition occurred with Notch activation in multipotential cells, prior to the initiation of endocrine differentiation. It has not been established how direct activation of Notch in endocrine precursor cells affects their subsequent cell fate. Using conditional activation of Notch in cells expressing Neurogenin3 or NeuroD1, we examined the effects of Notch in both organs, on cell fate of early endocrine precursors and maturing endocrine-restricted cells, respectively. Notch did not preclude the differentiation of a limited number of endocrine cells in either organ when activated in Ngn3⁺ precursor cells. In addition, in the pancreas most Ngn3⁺ cells adopted a duct but not acinar cell fate; whereas in intestinal Ngn3⁺ cells, Notch favored enterocyte and goblet cell fates, while selecting against endocrine and Paneth cell differentiation. A small fraction of NeuroD1⁺ cells in the pancreas retain plasticity to respond to Notch, giving rise to intraislet ductules as well as cells with no detectable pancreatic lineage markers that appear to have limited ultrastructural features of both endocrine and duct cells. These results suggest that Notch directly regulates cell fate decisions in multipotential early endocrine precursor cells. Some maturing endocrine-restricted NeuroD1⁺ cells in the pancreas switch to the duct lineage in response to Notch, indicating previously unappreciated plasticity at such a late stage of endocrine differentiation.     

Ultrastructural and autoradiographic analysis of the cellular reactivity of the exo- and endocrine epithelium of the frog pancreas under the action of cobalt chloride]

The frog pancreatic epithelium was studied using morphometry, autoradiography and electron microscopy during the treatment with cobalt chloride (10 mg/100 g body wieght). In response to this treatment, generative changes in some exocrine cells were revealed. At the same time, those of cells, whose nuclei were in the state of DNA synthesis, increased in number. Cobalt chloride resulted in endocrine A-cells damage. A compensation of the broken endocrine A-cell function was maintained in a transformation of the exocrine epithelium into endocrine A-cells and in the appearance of intermediate acinar-islet cells, as well as in islet A-cell hyperplasia.     

The 'Inka cell' and its associated cells: ultrastructure of the epitracheal glands in the gypsy moth,Lymantria dispar

The epitracheal glands in pharate and young pupae of Lymantria dispar are located at the base of ventrolateral tracheal trunks in the prothoracic and first through eighth abdominal segments. Each gland is composed of four cells the ultrastructure of which is described in this paper. One large cell and one smaller cell have an endocrine function, while a third cell is exocrine. A fourth cell forms a canal running from the exocrine cell into the trachea. The large endocrine cell, but not the smaller endocrine cell has released its secretions in freshly moulted pupae. The exocrine cell is assumed to be involved in the pupal moult events as well. The physiological role of the different cell types is discussed: The large endocrine cell (type I endocrine cell) is supposedly homologous with the 'Inka cell', which produces ecdysis triggering hormone (ETH) and was previously described in Manduca sexta; the functions of the smaller endocrine cell (type II endocrine cell) and the exocrine cell remain unknown.     

Microtopographic relation between the lymphatic capillaries and glands of the small intestine

Microtopographic interrelationships of the lymphatic capillaries and glands of the small intestine have been investigated taking into account new data on the diffuse endocrine system, which includes endocrine cells of the gastro-intestinal tract. An immediate contact of the lymphatic capillaries with the intestinal glands, resembling microtopographic interrelationships of the lymphatic capillaries in the endocrine glands, has been revealed in total translucent and histological preparations. A suggestion is made that the microtopographic interrelationships of the lymphatic capillaries and the intestinal glands can be regarded as a morphologic basis for absorption of hormones produced by the endocrine cells of the intestinal glands.     

Development of the endocrine pancreas during larval phases of Rana temporaria

Summary The pancreatic endocrine component was studied at different stages of development in the tadpoles of Rana temporaria. The material was embedded in Epon, and serial semithin and thin sections were made in order to correlate ultrastructural features and tinctorial traits of the endocrine cells. Serial semithin sections were also stained with the peroxidase-antiperoxidase immunocytochemical method and with silver impregnations for argyrophilia and argentaffinity. In early larvae (legless tadpoles), A and B cells are present. Both can be found within ducts and exocrine tissue or, more frequently, in cellular clusters among the ducts and acini. These primitive islets are solid structures, surrounded but not penetrated by capillaries. Mitoses were observed in A and B cells. In the following phase (tadpoles with hindlegs), D and pancreatic polypeptide-immunoreactive cells are also present, as well as numerous endocrine cells scattered among exocrine tissue. There is also a change in the vascular-insular pattern: capillaries not only surround but also penetrate the endocrine group. The structure of the endocrine pancreas in older tadpoles is similar. Tinctorial traits and ultrastructural features of endocrine cells are described, and the origin of primitive islets is discussed.     

Development of the Drosophila entero-endocrine lineage and its specification by the Notch signaling pathway

In this paper we have investigated the developmental–genetic steps that shape the entero-endocrine system of Drosophila melanogaster from the embryo to the adult. The process starts in the endoderm of the early embryo where precursors of endocrine cells and enterocytes of the larval midgut, as well as progenitors of the adult midgut, are specified by a Notch signaling-dependent mechanism. In a second step that occurs during the late larval period, enterocytes and endocrine cells of a transient pupal midgut are selected from within the clusters of adult midgut progenitors. As in the embryo, activation of the Notch pathway triggers enterocyte differentiation and inhibits cells from further proliferation or choosing the endocrine fate. The third step of entero-endocrine cell development takes place at a mid-pupal stage. Before this time point, the epithelial layer destined to become the adult midgut is devoid of endocrine cells. However, precursors of the intestinal midgut stem cells (pISCs) are already present. After an initial phase of symmetric divisions which causes an increase in their own population size, pISCs start to spin off cells that become postmitotic and express the endocrine fate marker, Prospero. Activation of Notch in pISCs forces these cells into an enterocyte fate. Loss of Notch function causes an increase in the proliferatory activity of pISCs, as well as a higher ratio of Prospero-positive cells.     

Purification of monolayer cell cultures of the endocrine pancreas

Experimental use of primary cultures of endocrine pancreas is constrained by early, vigorous proliferation of fibroblastoid cells. The addition of heavy metals, sodium ethylmercurithiosalicylate, phenyl mercuric acetate, phenyl mercuric nitrate and sodium aurothiomalate to the culture media selectively destroys these fibroblastoid cells yielding highly enriched, morphologically intact, functionally competent endocrine cells that are capable of cell replication. This action of heavy metals appears to be due to reversible inhibition of sulfhydryl enzymes since glutathione and thioglycolate were demonstrated to completely inhibit the cytotoxic effects of the mercury and gold containing agents, respectively. Certain variables in the application of the mercurial agents to pancreatic endocrine cell cultures were defined, most notably the enhanced sensitivity of fetal vs. neonatal tissue, and in inverse relationship of cell density to effective toxicity. After removal of the heavy metal agent from the culture media, many pancreatic islets send out cytoplasmic projections, containing large numbers of oriented microtubules which serve as bridging units to adjacent endocrine cells. The sustained availability of virtually pure pancreatic endocrine cell cultures, which results from the application of mercury to the culture media will undoubtedly permit many aspects of the cell biology of the endocrine pancreas to be directly and sequentially assailed.     

Ultrastructure and immunocytochemistry of endocrine cells in the midgut of the desert locust,Schistocerca gregaria (Forskal)

Summary The endocrine cells of the midgut epithelium of the desert locust are found dispersed among the digestive cells and are similar to those of the vertebrate gut. According to their reactivity to silver impregnation techniques and the ultrastructural features of the secretory granules (shape, electron-density, size, and structure) 10 types of endocrine cell have been identified, of which seven are located in the main segment of the midgut or in the enteric caeca, and the other three seem to be present only in the ampullae through which the Malpighian tubules drain into the gut. The endocrine cells have a slender cytoplasmic process that reaches the gut lumen, a feature that supports the receptosecretory nature postulated for this cellular type in insects as well as vertebrates. Antisera directed against mammalian gastrin, CCK, insulin, pancreatic polypeptide and bombesin reacted with some of the endocrine cells. This is the first time that insulin- and bombesin-like immunoreactive cells have been described in the midgut of an insect.     

Ontogeny of endocrine cells in the gut of the insect Periplaneta americana

Summary The ontogeny of the endocrine cells of the gut of the cockroach Periplaneta americana was studied by immunohistochemistry. During embryogenesis, the midgut begins to be formed as an outgrowth of the foregut and hindgut invaginations. Gut endocrine cells with pancreatic polypeptide (PP)-like immunoreactivity begin to appear at the anterior and posterior ends of the forming midgut. These cells are restricted to the midgut epithelium, and no mitotic cells with PP-like immunoreactivity are observed. These results strongly suggest that the gut endocrine cells, at least those with PP-like immunoreactivity, are derived from precursor cells they have in common with other epithelial cells of the midgut.     

Ultrastructure of midgut endocrine cells in the adult mosquito, Aedes aegypti

The ultrastructure of endocrine cells in the midgut of the adult mosquito, Aedes aegypti, resembled that of endocrine cells in the vertebrate gastro-intestinal tract. Midgut endocrine cells, positioned basally in the epithelium as single cells, were cone-shaped and smaller than the columnar digestive cells. The most distinctive characteristic of endocrine cells was numerous round secretory granules along the lateral and basal plasma membranes where contents of the granules were released by exocytosis. Secretory granules in each individual cell were exclusively of one type, either solid or 'haloed', and for all cells observed, the range in granule diameter was 60-120 nm. The cytoplasm varied in density from clear to dark. Lamellar bodies were prominent in the apical and lateral cellular regions and did not exhibit acid phosphatase activity. The basal plasma membrane was smooth adjacent to the basal lamina, whereas in digestive cells the membrane formed a labyrinth. Some endocrine cells reached the midgut lumen and were capped by microvilli; a system of vesicles and tubules extended from beneath the microvilli to the cell body. An estimated 500 endocrine cells were distributed in both the thoracic and abdominal regions of the adult midgut. In one midgut, we classified a sample of endocrine cells according to cytoplasmic density and granule type and size; endocrine cells with certain types of granules had specific distributions within the midgut.     

Endocrine function of the heart: structuro-functional aspects

Modern notions, accumulated during the period of investigation of before poorly studied endocrine++ function of the heart are presented. History of the problem, structural and functional aspects on argumentation of the cardiac endocrine function, place and role of physiologically active cardiac peptides in regulation of liquor and electrolytic homeostasis are followed, as well as interactions of the cardiac endocrine apparatus with the hormonal system of the organism. The authors' experience on the investigation connected with the problem is also demonstrated.     

Somatostatin-containing and other endocrine cells in the pancreas of the spectacled caiman

Light-microscopic immunocytochemistry was used to localize 4 major pancreatic hormones in the pancreas of the spectacled caiman, Caiman fuscus. Somatostatin, insulin, glucagon and pancreatic polypeptide were localized by the peroxidase-antiperoxidase complex technique. A relatively large population of somatostatin-containing D cells was present. The D cells were nearly as numerous as the insulin-containing B cells and glucagon-containing A cells which were the most common cell types. All three cell types were commonly intermingled with one another in endocrine cell areas. Pancreatic polypeptide-reactive F cells were absent from some regions of the pancreas, but where present were related to other endocrine cell types. Functional properties of the pancreatic endocrine cells in this anatomical variant remain to be determined.     

白条草蜥消化道内分泌细胞的免疫组织化学

应用6种胃肠激素抗血清和免疫组织化学ABC法(avidin-biotin complex method),对白条草蜥(Takydromus wolteri)消化道内分泌细胞进行了免疫组织化学定位研究和形态学观察。结果表明,5-羟色胺细胞较其他5种内分泌细胞的分布更为广泛,整个消化道中(即从食管到直肠)均有分布,其分布密度高峰位于幽门。食管、回肠和直肠未检测到生长抑素细胞,生长抑素细胞在幽门部分布密度最高,总体来说生长抑素细胞的分布在胃部较高而在小肠部较低。胃泌素细胞和胰多肽细胞分布在小肠,均在十二指肠分布密度最高。胰高血糖素细胞在胃幽门部分布密度最高,十二指肠、空肠次之,回肠分布密度最低。P-物质细胞仅分布于幽门部。6种内分泌细胞以圆形和锥体形为主,它们广泛分布于消化道黏膜之间、腺泡上皮细胞之间及上皮细胞基部。内分泌细胞的密度分布与其食性、食物组成和生活环境有关,它们的形态与其内、外分泌功能是相适应的。     

Seasonal changes of the ultrastructure of the pars tuberalis of the hypophysis of Rana temporaria

Summary In the pars tuberalis of the hypophysis of Rana temporaria, which shows the ultrastructural characteristics of a polypeptide hormone secreting endocrine gland, seasonal changes of the ultrastructure are described. In accordance with the literature, these seasonal changes of ultrastructure are interpreted as the morphological expression of seasonal changes of endocrine activity of the pars tuberalis.     

Endocrine cells of the esophageal glands]

Distribution of endocrine cells in the human oesophagus was studied histochemically. Large amount of endocrine cells was discovered in terminal parts and excretory ducts of the cardial glands. Endocrine cells of the oesophageal cardial glands are represented, at least, by three types: argentaffine, argyrophil in the reactions of Grimelius and Sevier, Munger and argyrophil in the reaction of Grimelius only. The amount of argentaffine cells in the oesophageal cardial glands was observed to be 5 times as large as that of in the gastric cardial glands. The reason is evidently in functional difference of the oesophageal and gastric cardial glands. The endocrine cells were absent in the mucous glands of the oesophagus.