Endocrine tissue associated with the pancreatic ductal system: A light and electron microscopic study of the adult rat pancreas with special reference to a new endocrine arrangement

Bertelli, Eugenio; Regoli, Marì; Bastianini, A

doi:10.1002/ar.1092390404

Cited by 24 publications

(14 citation statements)

References 27 publications

(34 reference statements)

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“…In addition, Agt may also be secreted into the excretory ducts through the multiple connections occurring between the endocrine compartment of the pancreas and the ductal tree (Park & Bendayan 1992, Bertelli et al 1994). This secretion could be favoured by the peripheral location of glucagon-secreting cells, since duct-islet contacts prevalently take place at the edge of the islets (Bertelli et al 2001).…”

Section: Discussionmentioning

confidence: 99%

Angiotensinogen localization and secretion in the rat pancreas

Regoli

Bendayan²,

Fonzi³

et al. 2003

Journal of Endocrinology

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Renin and angiotensinogen have been previously found in the rat pancreas, and angiotensin receptors have been located in the apical domain of duct cells. To evaluate the possibility that angiotensin II could be generated within the duct system, we decided to determine whether angiotensinogen is present in rat pancreatic juice and the angiotensinogen-immunoreactive pancreatic cell types that could be responsible for its production. Angiotensinogen was detected in significant amounts by Western blotting in pancreatic juice collected from several individual rats. Different isoforms between plasma and pancreatic juice angiotensinogens were demonstrated by isoelectric focusing. Immunocytochemical experiments revealed angiotensinogen-immunoreactive cells at the periphery of the islets of Langerhans, and confocal microscopy demonstrated that most angiotensinogenimmunoreactive cells were glucagon-secreting cells. Secretion of angiotensinogen did not follow the regulated secretory pathway since it was absent from the glucagoncontaining granules. This was confirmed by electron microscopy immunocytochemistry. Duct and acinar cells did not express angiotensinogen at an immunocytochemical detectable level. The present findings indicated an exocrine secretion of angiotensinogen by glucagonsecreting cells and suggest that one of the final targets of the local pancreatic renin-angiotensin system may be the duct epithelium.

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Section: Discussionmentioning

confidence: 99%

Angiotensinogen localization and secretion in the rat pancreas

Regoli

Bendayan²,

Fonzi³

et al. 2003

Journal of Endocrinology

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“…Moreover, most differentiated cells only undergo a limited number of mitotic cycles implying that the [3-cell population requires a continuous supply of undifferentiated cells with the potential for mitotic division after endocrine differentiation. In adult rats the occurrence of small islet cell buds attached to ducts has been interpreted as an indication of continuing neogenesis [4]. That duct cells have such a progenitor cell function is supported by the observation that the proliferative activity of islet (and acinar) cells decreases exponentially with age, whereas duct cells continue to proliferate at a relatively high rate [41].…”

Section: Replication Versus Neogenesismentioning

confidence: 99%

Islet cell neogenesis in the pancreas

Bouwens¹,

Klöppel

1996

Vichows Archiv A Pathol Anat

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The beta cell population of the endocrine pancreas may expand by either of two processes, neogenesis or replication. While replication requires the existence of an already differentiated beta cell, neogenesis depends on the presence of active stem cells. Since the replicative activity of highly specialized cells such as beta cells seems to be limited, it is interesting to study the potential of the endocrine pancreas for beta cell neogenesis. In this article we review both the current state of knowledge of beta cell neogenesis under natural conditions and in response to stimulation, and the significance of neogenesis for beta cell growth in health and disease.

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“…Endocrine cells have been previously reported to lie in the epithelial lining of pancreatic ducts as single elements [12,13] as well as to protrude as small buds into the surrounding tissue [14]. In the former case, cells were classified to be either an ªopenº or a ªclosed typeº depending on their ability to face the duct lumen.…”

Section: Discussionmentioning

confidence: 99%

Association between islets of Langerhans and pancreatic ductal system in adult rat. Where endocrine and exocrine meet together?

et al. 2001

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It is common to describe the endocrine and the exocrine pancreas as if they were two distinct and independent entities. However the pancreas is an integrated organ involved in the digestion and absorption of nutrients on the one hand, and in the regulation of blood glucose homeostasis, on the other. Most probably, the unique anatomical architecture of this organ, characterized by the dispersion of the endocrine component throughout the acinar parenchyma as hundreds of thousands variable-sized clusters of endocrine cells (islets of Langerhans), has evolved to facilitate interactions between the two glandular components [1]. In order to determine reciprocal influences, many aspects of the relations occurring between exocrine and endocrine pancreas have been investigated in the past three decades [2,3]. Because of the observation that, in contrast to ªtele-insularº acini, ªperi-insularº acini are formed by larger cells, containing more zymogen granules [2, 4±6], numerous studies have addressed the role(s) played by the islet hormones in tuning acinar cell secretion and the anatomical pathways, the so called ªislet-acinar axisª, through which this influence is exerted [2,3,7]. A large body of evidence indicates that a continuous insulo-acinar venous portal system conveys hormone enriched blood from the islets to the acinar parenchyma [2, 3, 8, 9]. The amount of acinar tissue that is ac- Diabetologia (2001) 44: 575±584 Association between islets of Langerhans and pancreatic ductal system in adult rat. Where endocrine and exocrine meet together? AbstractAims/hypothesis. Studies on the functional and morphological relations between exocrine and endocrine pancreas have been conducted mainly to disclose the influence of islets of Langerhans on acinar parenchyma. Less attention has been paid to the relations occurring between islets and pancreatic ducts. Methods. A series of consecutive sections of normal adult rat pancreas were double stained with islet (hormones) and duct (cytokeratin 20) markers. Electron microscopy was conducted to investigate the ultrastructural features of duct-islet relations and anti-insulin immunogold labelling was carried out to reveal the presence of insulin in the pancreatic duct system. Results. Consecutive double-stained sections demonstrated that 73.60 2.97 % of the islets were attached to the ducts. For each series, 93.48 5.43 % of the islets contacting the duct tree were associated with small-sized ducts or centroacinar cells. Electron microscopy revealed that some insulin and somatostatin cells do face the duct lumen. Insulin was detected within the duct lumen and in the endosomal compartment of the duct cells. Conclusions/interpretation. The finding that most islets are connected with the duct system in the adult pancreas is discussed in terms of hormone secretion into the ducts, islet histogenesis and the relation among the three tissue components of the pancreas, the endocrine, the exocrine and the duct system. [Diabetologia (2001) 44: 575±584]

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Endocrine tissue associated with the pancreatic ductal system: A light and electron microscopic study of the adult rat pancreas with special reference to a new endocrine arrangement

Abstract: The authors propose to explain the endocrine buds as components of the gastro-entero-pancreatic system or as a stage of an endocrine pancreatic "neo-histogenesis" occurring in the adult rat pancreas.

Cited by 24 publications

References 27 publications

Angiotensinogen localization and secretion in the rat pancreas

Angiotensinogen localization and secretion in the rat pancreas

Islet cell neogenesis in the pancreas

Association between islets of Langerhans and pancreatic ductal system in adult rat. Where endocrine and exocrine meet together?

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