摘要:

AbstractThe granular convoluted tubule (GCT) is a segment of the duct system of all rodents, situated between the striated and intercalated ducts. It has the peculiar property of synthesizing a large variety of biologically active polypeptides whose role in saliva remains unknown. The literature on the fine structure of GCT cells is critically reviewed. Some recent developments on endocrine regulation of the structure and contents of rodent GCT cells are summarized, with emphasis on EGF, NGF, renin, and kallikrein proteases. A survey of the distribution of GCT cells in several vertebrate families is presented. © 1994 Wiley‐Liss, I

ISSN:1059-910X    

DOI:10.1002/jemt.1070270102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractIn salivary glands and other exocrine organs, there are starfish‐shaped cells that lie between the basal lamina and the acinar and ductal cells. These have structural features of both epithelium and smooth muscle cells, and so are called myoepithelial cells. Their functions include contraction when the gland is stimulated to secrete, compressing or reinforcing the underlying parenchymal cells, thus aiding in the expulsion of saliva and preventing damage to the other cells. They also may aid in the propagation of secretory and other stimuli. Their common developmental origin with the basal cells of the larger ducts is displayed in the mature glands by shared structural and immunohistochemical features, but most such basal cells do not have the distinguishing features of myoepithelial cells, such as myofibrils. Although myoepithelial cells can be identified by light microscopy through enzyme histochemistry and special stains and immunohistochemistry for their myofibrils, these techniques can be misleading in salivary gland neoplasms. Thus, the most reliable means of identifying neoplastic myoepithelial cells is with a combination of histochemistry and electron microscopy. The extent to which these cells are derived from undifferentiated stem cells in both normal and neoplastic growth is controversial. The presentation here of transmission electron microscopy (TEM) of well‐differentiated myoepithelial cells in mitotic division indicates that stem cells are not necessarily the only source of myoepithelial cells in the later stages of salivary gland development or in neoplasia. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of A

ISSN:1059-910X    

DOI:10.1002/jemt.1070270103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractElectron microscopy has a limited role in the diagnosis of primary salivary gland tumors, although it can be helpful in metastatic lesions of possible salivary gland origin. The diversity of subtypes in salivary gland tumors, as well as the range of histomorphology within any one subtype, is unparalleled in any other human tumor. This and their relative infrequency causes diagnostic problems for pathologists. Ultrastructural techniques have been of major importance in determining the inter‐relationship of these tumors for classification purposes, revealing the subtle variations in common cellular differentiation pathways, determining the organization of tumor cells, and displaying the importance of extracellular matrix materials in establishing diagnostic criteria for each of the many subtypes. Electron microscopy has also been valuable in non‐neoplastic salivary gland disease and has an increasing role in experimental studies involving tissue from human and animal salivary parenchyma. © 1994 Wiley‐Lis

ISSN:1059-910X    

DOI:10.1002/jemt.1070270104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractEffects of experimental diabetes on rat submandibular glands have been documented, but earlier reports suggested that diabetes caused an extensive cellular degeneration and a replacement of the parenchymal cells by fibrous connective tissue. Such observations, however, are difficult to reconcile with the relatively normal physiological responsiveness of the gland (Anderson and Suleiman, 1989). This study, therefore, reexamined the histological, histochemical and ultrastructural effects of streptozotocin‐induced diabetes on rat submandibular glands. The tissues were examined at 3 weeks, and 3 and 6 months after the induction of diabetes, and compared with glands from age‐matched controls by both light and electron microscopy. Light microscopically, the proportional volumes of the acini and granular ducts remained constant in control rats at about 48% and 38% respectively. In diabetic animals the volume density of the acini increased progressively to 62%, whereas that of the granular ducts decreased to 20%. The diameter and number of granular ducts were reduced in diabetic animals, but acinar cell profile area was only affected 6 months after the induction of diabetes. Ultrastructurally, there was an accumulation of lipid in the acinar cells and, with increasing duration of diabetes, the number of autophagic structures in both the acini and the granular ducts increased. Although there was evidence of some cellular degeneration it was never excessive. Morphometry showed that the volume density of secretory granules within the acinar cells was unaffected, but there was a significant reduction in the volume density of secretory granules within the granular ducts. Thus, in the rat submandibular gland the greatest effect of streptozotocin‐induced diabetes was to cause hypotrophic changes in the cells of the granular ducts. The relative contributions of a direct effect of insulin insufficiency and the hypogonadal effects of diabetes, however, are not known. © 1994 Wiley‐L

ISSN:1059-910X    

DOI:10.1002/jemt.1070270105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractElectron probe X‐ray microanalysis (EPXMA) has now been successfully applied to several salivary gland preparations. This paper briefly reviews the principles underlying this technique and the specific sample preparation procedures which permit accurate measurement of elemental concentrations in the various intracellular spaces. Findings from salivary gland studies indicate that cytoplasmic and nuclear spaces of nonstimulated acinar cells have high concentrations of K and P, and low concentrations of Mg, Ca, and S; and that mature secretory granules have high concentrations of Ca and S, and relatively low concentrations of K and P. No consistent differences have been found between the elemental concentrations of mucous and serous secretory granules. In vivo and in vitro EPXMA studies of the elemental changes associated with secretory granule maturation indicate there are at least two stages in this process: an early stage during which granule S concentration increases in parallel with mass density as condensing vacuoles mature into secretory granules, and a late stage during which granule mass density and protein content increase with no further elemental concentration changes. Findings from other in vivo and in vitro studies indicate that secretory granule membranes are permeable to Na, K, and Cl ions because the granular concentrations of these elements are altered by electrochemical gradients. Recent EPXMA results indicate that cells stimulated with parasympathomimetic agonists have decreased K and Cl concentrations, and increased Na concentrations. Furthermore, the magnitude of these changes are quantitatively consistent with changes measured using radio‐isotope equilibration and other techniques. In contrast, cells stimulated with the β‐adrenergic agonist, isoproterenol, have increased concentrations of Na and Cl, but unchanged K concentrations. In terms of pathology, Na concentration is found to be elevated in secretory granules from labial salivary glands of patients with cystic fibrosis, but the pathophysiological consequences of this change are not known. Thus, studies utilizing EPXMA have obtained detailed and unique information about physiological and pathophysiological changes in elemental concentrations of intracellular organelles in salivary gland cells. © 1994 Wiley‐

ISSN:1059-910X    

DOI:10.1002/jemt.1070270106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070270101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY