DOCSLIB.ORG

Physiology of Duct Cell Secretion 7 Min Goo Lee and Shmuel Muallem

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Physiology of Duct Cell Secretion 7 Min Goo Lee and Shmuel Muallem 9781405146647_4_007.qxd 1/30/08 11:34 AM Page 78 Physiology of duct cell secretion 7 Min Goo Lee and Shmuel Muallem cells are in contact with centroacinar cells, which have several Introduction ductal characteristics and are regarded as the terminal cells of the ductal tree. The contents of the acini empty into the inter- calated, intralobular, and finally the interlobular ducts (Fig. The pancreas secretes digestive enzymes and a fluid rich in 7.2). In humans, the interlobular ducts join to form the main HCOϪ and poor in ClϪ. The digestive enzymes are synthesized 3 pancreatic duct, which shares a duodenal opening with the and secreted by the acinar cells, which also secrete a small vol- common bile duct at the ampulla of Vater. However, in rodents ume of an isotonic NaCl-rich fluid. The pancreatic duct secretes a number of interlobular ducts open directly into the common the bulk of the HCOϪ-rich fluid [1,2]. While exocytotic enzyme 3 pancreaticobiliary duct without forming a main duct. secretion by acinar cells has been studied extensively [3], the In the human pancreas, the intercalated and the small molecular mechanism of fluid secretion by the duct is only intralobular ducts are the major sites of HCOϪ secretion. In the partially understood [1]. This is despite the fact that we now 3 mouse and rat, the interlobular duct secretes the bulk of the know that impaired ductal secretion leads to destruction of the fluid and HCOϪ [11]. The HCOϪ-secreting portion of these pancreas, as occurs in cystic fibrosis [4,5], and may contribute 3 3 ducts is lined by the principal cells, which share common char- to other diseases of the pancreas including alcohol-associated acteristics. They contain a relatively small amount of rough chronic pancreatitis [6]. Hence beside its intrinsic interest, endoplasmic reticulum, Golgi complexes, and secretory vesicles, understanding the mechanisms of pancreatic ductal fluid and but are rich in mitochondria in order to satisfy the energy electrolyte secretion has an immediate link to a better under- requirements of active HCOϪ secretion. The luminal (apical) standing of common pancreatic diseases. 3 membrane of the principal cell possesses microvilli. The lateral The ductal tree provides a structural framework for acinar membranes are interdigitated and linked by tight and adherent and endocrine tissues, secretes fluid that acts as a vehicle for junctions and by desmosomes. In the larger ducts the principal the transport of digestive enzymes, and secretes HCOϪ that 3 cells become columnar and the duct contains goblet cells, which neutralizes gastric acid and provides an optimum pH environ- are specialized in secreting mucins. ment for digestive enzymes in the duodenum [2,7]. An over- Ϫ Ϫ looked function of HCO3 secretion is that HCO3 is a chaotropic ion that is important for the solubilization of Composition of pancreatic juice macromolecules in order to prevent the aggregation of digestive enzymes and mucins. This chapter focuses on the molecular The human pancreas secretes 1–2 L of pancreatic juice per day in Ϫ mechanisms of fluid and HCO3 secretion and their regulation response to physiologic stimuli, mainly secretin and vagal output. Ϫ and attempts to explain how the duct secretes HCO3 at a con- The pancreatic juice is a clear, alkaline, isotonic fluid. The human centration more than five times higher than that found in pancreatic duct can secrete a fluid containing 120–140 mmol/L Ϫ Ϫ plasma. HCO3 [12]; however, in the rat the HCO3 concentration is Ϫ about 70 mmol/L [13]. The HCO3 content in the juice increases Ϫ with increased flow rate. Peak HCO3 content is reached at Structure of the ductal tree Ϫ 30–50% of maximal flow. The reciprocal Cl absorption and HCOϪ secretion results in isotonic osmolality at all flow rates The pancreas develops from the ventral and dorsal surfaces of 3 (Fig. 7.3) [13–15]. The cation composition of the juice is nearly the primitive foregut, and the two parts later fuse to form a com- constant (140 mmol/L Naϩ and 10–15 mmol/L Kϩ) regardless of plex endocrine–exocrine organ. Acinar and islet cells are derived flow rate. Human pancreatic juice also contains 1–2 mmol/L from the ductal bud, which has stem cell-like properties. Even Ca2ϩ and a small amount of Mg2ϩ, Zn2ϩ, PO3Ϫ, and SO2Ϫ. after completion of morphogenesis, duct cells retain some prolif- 4 4 erative capacity in order to generate new duct and islet cells [8]. In humans and most other mammals, duct cells comprise Regulation of pancreatic secretion about 10% of the number of cells and 5% of the total mass of the pancreatic gland [9]. The duct endings are connected to a The principle involved in the control of pancreatic fluid and elec- group of acinar cells to form the acini (Fig. 7.1). The acinar trolyte secretion is that of the common neurohumoral control 78 9781405146647_4_007.qxd 1/30/08 11:34 AM Page 79 PHYSIOLOGY OF DUCT CELL SECRETION (a) (b) A D D A Figure 7.1 (a) Scanning electron microscopic view of rat pancreatic lobules. Arrows indicate a long intercalated duct. (b) Scanning electron microscopic view of rat pancreatic ducts after removal of most acini by ultrasonic vibration. Arrows indicate intercalated ducts. (From ref. 10 with permission.) Acinar cell Pancreatic enzymes 160 Na HCO3 120 Centroacinar cell 80 Water Duct cell NaHCO3 40 Ion concentration (mmol/L) CI Intercalated duct K 04 8 121620 Interlobular duct Intralobular duct Pancreatic secretion rate (µL/g/min) Figure 7.2 Schematic diagram of the pancreatic exocrine system. The Figure 7.3 Composition of pancreatic juice at different flow rates endings of the terminal duct are connected to a group of acinar cells in the cat in response to secretin stimulation. The reciprocal ClϪ to form an acinus. The contents of the acini empty into intercalated Ϫ absorption and HCO3 secretion results in juice with isotonic ducts, intralobular ducts and, in turn, small and large interlobular osmolality regardless of flow rate. (From ref. 16 with permission.) ducts. The pancreatic duct secretes the bulk of the fluid in the Ϫ pancreatic juice that is rich in HCO3 . of gastrointestinal secretion as proposed over 100 years ago human. When informative, data obtained with genetically [17,18], and includes vagal and secretin stimulation. However, manipulated mice are also discussed. Additional information recent findings indicate that the regulation of pancreatic secre- can be found in references 7 and 15. tion is more complex, with numerous stimulatory and inhibitory inputs [19]. Another consideration when studying pancreatic Interdigestive secretion secretion is the highly species-specific pattern of secretion. In this chapter, we emphasize the physiology of the human pan- In dogs and possibly in humans, interdigestive (resting) pancre- Ϫ creas, and list information obtained with the guinea-pig atic HCO3 and digestive enzyme secretion is less than 2% Ϫ pancreas, the secretion of which most resembles that of the and 10% of the maximum, respectively [20]. Ductal HCO3 79 9781405146647_4_007.qxd 1/30/08 11:34 AM Page 80 CHAPTER 7 Ϫ salvage mechanisms contribute to the low basal HCO3 output its secretion. Cells in the islets of Langerhan release insulin, [21]. During the interdigestive period, transient bursts of secre- somatostatin, and several other peptide hormones that affect tion occur every 1–2 hours. This coincides with the cyclical ductal and acinar secretion. These agents are present at rela- motor activity of the upper gastrointestinal tract (interdigestive tively high concentration and reach their target through the migrating motor complex, IMMC). Gastric and biliary secre- insuloacinar portal system [29]. Other agonists, including tion, and blood levels of motilin and pancreatic polypeptide (PP), purines, prostaglandins, and activated trypsin, are released by also increase along with the IMMC. The IMMC is generated by either acinar or duct cells and regulate ductal function in circulating motilin and by cholinergic stimulation [22]. The pre- numerous physiologic and pathologic states. Receptors for cise physiologic significance of the IMMC is uncertain. these agonists (autacoids, paracrine) are expressed in both the luminal and the basolateral membranes of the duct. Both the extrinsic and the intrinsic nervous systems partici- Response to a meal pate in the neuronal control of pancreatic secretion. Nerve Ϫ Pancreatic HCO3 and enzyme secretion are increased in fibers travel through the lamina propria of the intercalated, response to a meal. Control of pancreatic secretion is divided interlobular, and main ducts. The nerve terminals are located into the cephalic, gastric, and intestinal phases. Secretion by in close proximity to the duct basal membrane [30]. In this acinar cells is controlled by the cephalic and gastric inputs. manner the neurotransmitters diffuse only a short distance, For example, sham feeding with visual, olfactory, and gusta- retain a high concentration at their effector sites, and produce tory stimuli increases enzyme secretion by up to 50% of max- a relatively rapid response. Some agonists, such as ATP, are imum in humans [23]. Gastric distension with a balloon also released by both neuron and the pancreatic acinar and duct increases enzyme output [24]. However, both stimuli have lit- cells and activate the same class of receptors [31]. Ϫ tle effect on ductal HCO3 and fluid secretion. The intestinal phase is the most important phase for meal- Endocrine and paracrine control of ductal secretion induced pancreatic secretion and commences with the passage of chyme into the proximal duodenum. Secretin, secreted by Secretin cells in the upper duodenum, and an enteropancreatic vago- The entry of acidic chyme into the duodenum evokes the release vagal reflex are the two principal mechanisms that induce ductal Ϫ of secretin from neuroendocrine cells in the duodenal mucosa.
Load more

Recommended publications
  • Pancreatic B-Cell Replacement: Advances in Protocols Used for Differentiation of Pancreatic Progenitors to B-Like Cells
    FOLIA HISTOCHEMICA REVIEW ET CYTOBIOLOGICA Vol. 57, No. 3, 2019 pp. 101–115 Pancreatic b-cell replacement: advances in protocols used for differentiation of pancreatic progenitors to b-like cells Muhammad Waseem Ghani1, Li Ye1, Zhao Yi1, Hammad Ghani2, Muhammad Waseem Birmani1, Aamir Nawab1, Lang Guan Cun1, Liu Bin1, Xiao Mei1 1Department of Livestock Production and Management, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, China 2Nawaz Sharif Medical College University of Gujrat, Punjab, Pakistan Abstract Insulin-producing cells derived from in vitro differentiation of stem cells and non-stem cells by using different factors can spare the need for genetic manipulation and provide a cure for diabetes. In this context, pancreatic progenitors differentiating to b-like cells garner increasing attention as b-cell replacement source. This kind of cell therapy has the potential to cure diabetes, but is still on its way of being clinically useful. The primary restriction for in vitro production of mature and functional b-cells is developing a physiologically relevant in vitro culture system which can mimic in vivo pathways of islet development. In order to achieve this target, different approaches have been attempted for the differentiation of pancreatic stem/progenitor cells to b-like cells. Here, we will review some of the state-of-the-art protocols for the differentiation of pancreatic progenitors and differentiated pancreatic cells into b-like cells with a focus on pancreatic duct cells. (Folia Histochemica et Cytobiologica
    [Show full text]
  • Vocabulario De Morfoloxía, Anatomía E Citoloxía Veterinaria
    Vocabulario de Morfoloxía, anatomía e citoloxía veterinaria (galego-español-inglés) Servizo de Normalización Lingüística Universidade de Santiago de Compostela COLECCIÓN VOCABULARIOS TEMÁTICOS N.º 4 SERVIZO DE NORMALIZACIÓN LINGÜÍSTICA Vocabulario de Morfoloxía, anatomía e citoloxía veterinaria (galego-español-inglés) 2008 UNIVERSIDADE DE SANTIAGO DE COMPOSTELA VOCABULARIO de morfoloxía, anatomía e citoloxía veterinaria : (galego-español- inglés) / coordinador Xusto A. Rodríguez Río, Servizo de Normalización Lingüística ; autores Matilde Lombardero Fernández ... [et al.]. – Santiago de Compostela : Universidade de Santiago de Compostela, Servizo de Publicacións e Intercambio Científico, 2008. – 369 p. ; 21 cm. – (Vocabularios temáticos ; 4). - D.L. C 2458-2008. – ISBN 978-84-9887-018-3 1.Medicina �������������������������������������������������������������������������veterinaria-Diccionarios�������������������������������������������������. 2.Galego (Lingua)-Glosarios, vocabularios, etc. políglotas. I.Lombardero Fernández, Matilde. II.Rodríguez Rio, Xusto A. coord. III. Universidade de Santiago de Compostela. Servizo de Normalización Lingüística, coord. IV.Universidade de Santiago de Compostela. Servizo de Publicacións e Intercambio Científico, ed. V.Serie. 591.4(038)=699=60=20 Coordinador Xusto A. Rodríguez Río (Área de Terminoloxía. Servizo de Normalización Lingüística. Universidade de Santiago de Compostela) Autoras/res Matilde Lombardero Fernández (doutora en Veterinaria e profesora do Departamento de Anatomía e Produción Animal.
    [Show full text]
  • Nomina Histologica Veterinaria, First Edition
    NOMINA HISTOLOGICA VETERINARIA Submitted by the International Committee on Veterinary Histological Nomenclature (ICVHN) to the World Association of Veterinary Anatomists Published on the website of the World Association of Veterinary Anatomists www.wava-amav.org 2017 CONTENTS Introduction i Principles of term construction in N.H.V. iii Cytologia – Cytology 1 Textus epithelialis – Epithelial tissue 10 Textus connectivus – Connective tissue 13 Sanguis et Lympha – Blood and Lymph 17 Textus muscularis – Muscle tissue 19 Textus nervosus – Nerve tissue 20 Splanchnologia – Viscera 23 Systema digestorium – Digestive system 24 Systema respiratorium – Respiratory system 32 Systema urinarium – Urinary system 35 Organa genitalia masculina – Male genital system 38 Organa genitalia feminina – Female genital system 42 Systema endocrinum – Endocrine system 45 Systema cardiovasculare et lymphaticum [Angiologia] – Cardiovascular and lymphatic system 47 Systema nervosum – Nervous system 52 Receptores sensorii et Organa sensuum – Sensory receptors and Sense organs 58 Integumentum – Integument 64 INTRODUCTION The preparations leading to the publication of the present first edition of the Nomina Histologica Veterinaria has a long history spanning more than 50 years. Under the auspices of the World Association of Veterinary Anatomists (W.A.V.A.), the International Committee on Veterinary Anatomical Nomenclature (I.C.V.A.N.) appointed in Giessen, 1965, a Subcommittee on Histology and Embryology which started a working relation with the Subcommittee on Histology of the former International Anatomical Nomenclature Committee. In Mexico City, 1971, this Subcommittee presented a document entitled Nomina Histologica Veterinaria: A Working Draft as a basis for the continued work of the newly-appointed Subcommittee on Histological Nomenclature. This resulted in the editing of the Nomina Histologica Veterinaria: A Working Draft II (Toulouse, 1974), followed by preparations for publication of a Nomina Histologica Veterinaria.
    [Show full text]
  • Interaction of Stellate Cells with Pancreatic Carcinoma Cells
    Cancers 2010, 2, 1661-1682; doi:10.3390/cancers2031661 OPEN ACCESS cancers ISSN 2072-6694 www.mdpi.com/journal/cancers Review Interaction of Stellate Cells with Pancreatic Carcinoma Cells Hansjörg Habisch 1, Shaoxia Zhou 1, Marco Siech 2 and Max G. Bachem 1,* 1 Department Clinical Chemistry and Central Laboratory, University of Ulm, Germany; E-Mails: [email protected] (H.H); [email protected] (S.Z.) 2 Department of surgery, Ostalbklinikum Aalen, Germany; E-Mail: [email protected] (M.S.) * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +49-731-500-67500/01; Fax: +49-731-500-67506. Received: 28 July 2010; in revised form: 2 September 2010 / Accepted: 2 September 2010 / Published: 9 September 2010 Abstract: Pancreatic cancer is characterized by its late detection, aggressive growth, intense infiltration into adjacent tissue, early metastasis, resistance to chemo- and radiotherapy and a strong ―desmoplastic reaction‖. The dense stroma surrounding carcinoma cells is composed of fibroblasts, activated stellate cells (myofibroblast-like cells), various inflammatory cells, proliferating vascular structures, collagens and fibronectin. In particular the cellular components of the stroma produce the tumor microenvironment, which plays a critical role in tumor growth, invasion, spreading, metastasis, angiogenesis, inhibition of anoikis, and chemoresistance. Fibroblasts, myofibroblasts and activated stellate cells produce the extracellular matrix components and are thought to interact actively with tumor cells, thereby promoting cancer progression. In this review, we discuss our current understanding of the role of pancreatic stellate cells (PSC) in the desmoplastic response of pancreas cancer and the effects of PSC on tumor progression, metastasis and drug resistance.
    [Show full text]
  • Normal Pancreatic Function 1. What Are the Functions of the Pancreas?
    Normal Pancreatic Function Stephen J. Pandol Cedars-Sinai Medical Center and Department of Veterans Affairs Los Angeles, California USA [email protected] Version 1.0, June 13, 2015 [DOI: 10.3998/panc.2015.17] 1. What are the functions of the This chapter presents processes underlying the functions of the exocrine pancreas with pancreas? references to how specific abnormalities of the The pancreas has both exocrine and endocrine pancreas can lead to disease states. function. This chapter is devoted to the exocrine functions of the pancreas. The exocrine function 2. Where is the pancreas located? is devoted to secretion of digestive enzymes, ions and water into the intestine of the gastrointestinal The illustration in Figure 1 demonstrates the (GI) tract. The digestive enzymes are necessary anatomical relationships between the pancreas for converting a meal into molecules that can be and organs surrounding it in the abdomen. The absorbed across the surface lining of the GI tract regions of the pancreas are the head, body, tail into the body. Of note, there are digestive and uncinate process (Figure 2). The distal end enzymes secreted by our salivary glands, of the common bile duct passes through the head stomach and surface epithelium of the GI tract of the pancreas and joins the pancreatic duct as it that also contribute to digestion of a meal. enters the intestine (Figure 2). Because the bile However, the exocrine pancreas is necessary for duct passes through the pancreas before entering most of the digestion of a meal and without it the intestine, diseases of the pancreas such as a there is a substantial loss of digestion that results cancer at the head of the pancreas or swelling in malnutrition.
    [Show full text]
  • Índice De Denominacións Españolas
    VOCABULARIO Índice de denominacións españolas 255 VOCABULARIO 256 VOCABULARIO agente tensioactivo pulmonar, 2441 A agranulocito, 32 abaxial, 3 agujero aórtico, 1317 abertura pupilar, 6 agujero de la vena cava, 1178 abierto de atrás, 4 agujero dental inferior, 1179 abierto de delante, 5 agujero magno, 1182 ablación, 1717 agujero mandibular, 1179 abomaso, 7 agujero mentoniano, 1180 acetábulo, 10 agujero obturado, 1181 ácido biliar, 11 agujero occipital, 1182 ácido desoxirribonucleico, 12 agujero oval, 1183 ácido desoxirribonucleico agujero sacro, 1184 nucleosómico, 28 agujero vertebral, 1185 ácido nucleico, 13 aire, 1560 ácido ribonucleico, 14 ala, 1 ácido ribonucleico mensajero, 167 ala de la nariz, 2 ácido ribonucleico ribosómico, 168 alantoamnios, 33 acino hepático, 15 alantoides, 34 acorne, 16 albardado, 35 acostarse, 850 albugínea, 2574 acromático, 17 aldosterona, 36 acromatina, 18 almohadilla, 38 acromion, 19 almohadilla carpiana, 39 acrosoma, 20 almohadilla córnea, 40 ACTH, 1335 almohadilla dental, 41 actina, 21 almohadilla dentaria, 41 actina F, 22 almohadilla digital, 42 actina G, 23 almohadilla metacarpiana, 43 actitud, 24 almohadilla metatarsiana, 44 acueducto cerebral, 25 almohadilla tarsiana, 45 acueducto de Silvio, 25 alocórtex, 46 acueducto mesencefálico, 25 alto de cola, 2260 adamantoblasto, 59 altura a la punta de la espalda, 56 adenohipófisis, 26 altura anterior de la espalda, 56 ADH, 1336 altura del esternón, 47 adipocito, 27 altura del pecho, 48 ADN, 12 altura del tórax, 48 ADN nucleosómico, 28 alunarado, 49 ADNn, 28
    [Show full text]
  • University of Southampton Research Repository Eprints Soton
    University of Southampton Research Repository ePrints Soton Copyright © and Moral Rights for this thesis are retained by the author and/or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the copyright holder/s. The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the copyright holders. When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given e.g. AUTHOR (year of submission) "Full thesis title", University of Southampton, name of the University School or Department, PhD Thesis, pagination http://eprints.soton.ac.uk UNIVERSITY OF SOUTHAMPTON REGULATION OF THE SYNTHESIS OF TISSUE INHIBITORS OF METALLOPROTEINASE-1 AND –2 BY HEPATIC AND PANCREATIC STELLATE CELLS Dr Peter Raymond McCrudden B.Sc.(Hons) MBBS FRCP Submitted for the degree of MD Faculty of Medicine, Health and Biological Sciences June 2010 For Ute, Nicolas, Katia and India 2 UNIVERSITY OF SOUTHAMPTON ABSTRACT FACULTY OF MEDICINE, HEALTH AND LIFE SCIENCES (MHLS) SCHOOL OF MEDICINE DIVISION OF INFECTION, INFLAMMATION AND IMMUNITY Doctor of Medicine REGULATION OF THE SYNTHESIS OF TISSUE INHIBITORS OF METALLOPROTEINASE-1 AND –2 BY HEPATIC AND PANCREATIC STELLATE By Dr Peter Raymond McCrudden Hepatic stellate cells (HSC) play a central role in fibrosis development by production of extracellular matrix and also by secretion of matrix metalloproteinases (MMPs) and Tissue inhibitors of metalloproteinases (TIMPs) including TIMP-2 and MMP-2.
    [Show full text]
  • Extensive Pancreas Regeneration Following Acinar-Specific
    GASTROENTEROLOGY 2011;141:1463–1472 Extensive Pancreas Regeneration Following Acinar-Specific Disruption of Xbp1 in Mice DAVID A. HESS,* SEAN E. HUMPHREY,* JEFF ISHIBASHI,* BARBARA DAMSZ,* ANN–HWEE LEE,‡ LAURIE H. GLIMCHER,‡ and STEPHEN F. KONIECZNY* *Department of Biological Sciences and the Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana; and ‡Department of Immunology and Infectious Diseases, Harvard School of Public Health, and Department of Medicine, Harvard Medical School, Boston, Massachusetts and survival of acinar cells is the management of their See editorial on page 1155. extensive protein synthesis/processing machinery, which uses regulatory pathways involving the Golgi, intermediate BACKGROUND & AIMS: Progression of diseases of the transport vesicles, plasma membrane components, and the exocrine pancreas, which include pancreatitis and cancer, is endoplasmic reticulum (ER). Among these organelles, the associated with increased levels of cell stress. Pancreatic aci- ER ensures that newly synthesized secretory and transmem- nar cells are involved in development of these diseases and, brane proteins are properly folded and modified before ex- because of their high level of protein output, they require an portation. In cells with high protein synthesis demands,2,3 efficient, unfolded protein response (UPR) that mediates with specific differentiation requirements,2,4,5 or that are recovery from endoplasmic reticulum (ER) stress following subject to environmental or physiologic alterations, the abil- the accumulation of misfolded proteins. METHODS: To ity of the protein-folding machinery to handle the synthetic study recovery from ER stress in the exocrine organ, we load can reach an imbalance, setting in motion a series of generated mice with conditional disruption of Xbp1 (a prin- intracellular signaling pathways collectively known as the cipal component of the UPR) in most adult pancreatic aci- unfolded protein response (UPR).6–8 Activation of the UPR nar cells (Xbp1fl/fl).
    [Show full text]
  • HISTOLOGY & CELL BIOLOGY Mr. BABATUNDE, D.E DIGESTIVE
    HISTOLOGY & CELL BIOLOGY Mr. BABATUNDE, D.E DIGESTIVE GLANDS I EXTRINSIC GLANDS ❖ Of the digestive system are located outside the wall of the alimentary canal and deliver their secretion into the lumen via a system of ducts. ❖ Provide enzymes, buffers, emulsifiers, and lubricants for the digestive tract, as well as hormones, proteins, globulins, and numerous additional products for the remainder of the body. ❖ Are the salivary glands (parotid, sublingual, and submandibular), the pancreas, and the liver. MAJOR SALIVARY GLANDS Parotid Gland Classification ❖ Purely serous, compound, tubuloalveolar gland. Capsule ❖ Formed by the continuation of the superficial cervical fascia, is mostly collagenous in nature. ❖ Forms broad bands of trabeculae (septa) that subdivide the gland into lobes and lobules. Trabeculae ❖ Convey blood and lymph vessels, ducts, and nerves into the substance of the gland. ❖ Often contain fat cells in older individuals. Acini ❖ Although are said to be composed of purely serous cells, they are actually seromucous in character. ❖ Are surrounded by myoepithelial cells. ❖ Their center contains the lumen. Parotid gland : only contains serous secretory units Figure 16—2. Photomicrograph of a parotid gland. Its secretory portion consists of serous amylase—producing cells that store this enzyme in secretory granules. Intralobular (intercalated and striated) ducts are also present. Pararosaniline— toluidine blue (PT) stain. Medium magnification. Acinar Cells ❖ Pyramidal cells, whose apical aspects usually contain secretory granules. ❖ Nucleus is round and basally located. ❖ Cytoplasm contains extensive rough endoplasmic reticulum, a well-developed Golgi apparatus, and numerous mitochondria. Myoepithelial Cells ❖ Are stellate shaped. ❖ Their cytoplasm is difficult to discern with the light microscope. ❖ Electron micrographs demonstrate that they resemble smooth muscle cells and are contractile.
    [Show full text]
  • Cellular and Molecular Mechanisms of Pancreatitis in Atrophy and Regeneration
    Cellular and molecular mechanisms of pancreatitis in atrophy and regeneration Lynne Estelle Reid BSc, MSc (Qual) A thesis submitted for the degree of Doctor of Philosophy at The University of Queensland in 2018 Faculty of Medicine i ABSTRACT Pancreatitis is a debilitating disease with complex etiology, prognosis and pathology, limited treatment options and a burden on health resources. The main lesions of acute pancreatitis are injury to acinar cells and inflammation of the pancreas. Mild interstitial pancreatitis (or oedematous pancreatitis) is characterized by acute inflammation with oedema in the stroma and acinar tissue. Necrosis of acinar tissue, stroma or peri-pancreatic fat is absent and complete recovery, or regeneration of the gland is usual. Whilst there is universal agreement on many of the cellular changes that accompany acute pancreatitis, there is no clear distinction between the factors that determine whether regeneration can occur. The mechanism of regeneration and the cellular processes that influence regeneration form the primary basis of this study. Experimental models of pancreatitis have been produced in rats, mice, dogs, cats and swine by various methods. The time course and final tissue regeneration, if it occurs, vary considerably among different models, with many having the limitation that pancreatic injury is extended, so that degenerative processes are superimposed on regenerative activity. Three in vivo models of pancreatitis in rats were chosen for this project, to study pancreatitis and pancreatic regeneration that occurs in the recovery phase. These models evolve slowly, allowing detailed morphological study. In general, they have similar early events but vary considerably in regenerative outcome. (1) The infusion of caerulein is a well-established model for inducing experimental pancreatitis in rats and pancreatitis is followed by a great reparative capacity.
    [Show full text]
  • Centroacinar Cells Are Progenitors That Contribute to Endocrine Pancreas
    Page 1 of 50 Diabetes Centroacinar cells are progenitors that contribute to endocrine pancreas regeneration. Fabien Delaspre*1, Rebecca L. Beer*1, Meritxell Rovira2, Wei Huang1, Guangliang Wang1, Stephen Gee1, Maria del Carmen Vitery1, Sarah J. Wheelan1, 3, and Michael J. Parsons1, 4† 1 McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University, Baltimore, MD 2 Genomic Programming of Beta-Cells Laboratory, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain 3 Department of Oncology, Johns Hopkins University, Baltimore, MD 4 Department of Surgery, Johns Hopkins University, Baltimore, MD * Authors contributed equally to this work † Corresponding author [email protected] Short title: CACs are β-cell progenitors Correspondence: Michael J. Parsons, Johns Hopkins University School of Medicine, 733 N. Broadway, MRB 467, Baltimore, MD 21205; [email protected] 3,994 words, 7 Figures 1 Diabetes Publish Ahead of Print, published online July 7, 2015 Diabetes Page 2 of 50 Abstract Diabetes is associated with a paucity of insulin-producing β cells. With the goal of finding therapeutic routes to treat diabetes, we aim to find molecular and cellular mechanisms involved in β-cell neogenesis and regeneration. To facilitate discovery of such mechanisms we utilize a vertebrate organism where pancreatic cells readily regenerate. The larval zebrafish pancreas contains Notch-responsive progenitors that during development give rise to adult ductal, endocrine, and centroacinar cells (CACs). Adult CACs are also Notch-responsive and are morphologically similar to their larval predecessors. To test our hypothesis that adult CACs are also progenitors we took two complementary approaches: 1) we established the transcriptome for adult CACs.
    [Show full text]
  • Single-Cell Resolution Analysis of the Human Pancreatic Ductal Progenitor Cell Niche
    Single-cell resolution analysis of the human pancreatic ductal progenitor cell niche Mirza Muhammad Fahd Qadira,b,1, Silvia Álvarez-Cubelaa,1, Dagmar Kleina, Jasmijn van Dijkc, Rocío Muñiz-Anquelad, Yaisa B. Moreno-Hernándeza,e, Giacomo Lanzonia, Saad Sadiqf, Belén Navarro-Rubioa,e, Michael T. Garcíaa, Ángela Díaza, Kevin Johnsona, David Santg, Camillo Ricordia,h,i,j,k, Anthony Griswoldl, Ricardo Luis Pastoria,l,2, and Juan Domínguez-Bendalaa,b,h,2 aDiabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL 33136; bDepartment of Cell Biology and Anatomy, University of Miami Miller School of Medicine, Miami, FL 33136; cInstituut voor Life Science & Technology, Hanze University of Applied Sciences, 9747 AS Groningen, The Netherlands; dVrije Universiteit Medisch Centrum School of Medical Sciences, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands; eFacultad de Medicina, Universidad Francisco de Vitoria, 28223 Madrid, Spain; fDepartment of Electrical and Computer Engineering, University of Miami, Coral Gables, FL 33146; gDepartment of Biomedical Informatics, University of Utah, Salt Lake City, UT 84108; hDepartment of Surgery, University of Miami Miller School of Medicine, Miami, FL 33136; iDepartment of Microbiology & Immunology, University of Miami Miller School of Medicine, Miami, FL 33136; jDepartment of Biomedical Engineering, University of Miami Miller School of Medicine, Miami, FL 33136; kDepartment of Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Miami Miller
    [Show full text]