Ultrastructure of the human submandibular salivary glands]

By means of electron microscopy cells in the human submandibular glands were studied. It was demonstrated that in acini two types of glandular cells were present: mucosal and seromucosal. In the latter, secretory granules are descrete with electron opaque cores in most of them. Mucocytes are filled with an electron transparent secrete; secretory granules often confluent and their membranes rupture. The acini are surrounded with myoepithelial cells. Intercalated ducts consist of cells with moderately electron opaque granules. In some granules there are dense bodies excentrically situated. In these cells there occur lipid inclusions. Striated ducts are composed of basal (electron transparent) and high cylindric (light and dark) cells. The cylindrical cells have a large amount of mitochondria, deep folds in their basal plasmolemma protruding into cytoplasma. Most of the cells in these parts contain small apically accumulated secretory granules with a dense matrix and separate larger ones scattered in the cell. It is possible to suggest that some secretory granules of ductal or, perhaps, acinar origin contain hormonal products.     

Reaction of the salivary glands to acute stress]

Experiment on male rats has shown that acute stress suppressed amylase and superoxide dismutase activity in the submandibular salivary glands. The influence of short repeated stresses weakened the inhibiting effect of the acute stress on the activity of enzymes. A conclusion is drawn about the high sensibility of salivary glands to stress influences.     

The histology and ultrastructure of the salivary glands of Neopanorpa longiprocessa (Mecoptera: Panorpidae)

The salivary glands of Panorpidae usually exhibit distinct sexual dimorphism and are closely related to the nuptial feeding behavior. In this study, the salivary glands of Neopanorpa longiprocessa were investigated using light microscopy and transmission electron microscopy. The salivary glands are tubular labial glands and consist of a scoop-shaped salivary pump, a common salivary duct, and a pair of salivary tubes. The male and female salivary glands are remarkably different in the bifurcation position of the common salivary duct and the length and shape of the secretory tubes. Compared with the simple female salivary glands, the male’s are more developed as their paired elongated salivary tubes can be divided into two parts, the glabrate anterior tube and the posterior tube with many secretory tubules. The ultrastructural study shows that the male salivary tubes have strong secretory function. The existence of different secretion granules indicates that there are some chemical reactions or mixing occurring in the lumen. Based on the ultrastructural characteristics, the functions of the different regions of the salivary tube have been speculated. The relationship between the salivary glands and nuptial feeding behavior of N. longiprocessa has been briefly discussed based on the structure of the salivary glands.

     

Quantitative histoenzymologic characteristics of the human submandibular salivary glands]

Quantitative activity of oxidative-reductive and hydrolytic enzymes obtained during operation was investigated in different parts of the human submandibular salivary glands. Quantitative estimation of enzymic activity was done by photometry of the negatives prepared on MY-phi-6. Comparative examination of enzymatic activity made it possible to state that according to the peculiarities of metabolic processes, the cells of striated and intralobular secreting ducts are similar to the cells of the secreting terminal parts. A high activity of NADP-diaphorase, G-6-PhDG and acid phosphatase in the epithelium of the secreting ducts, and parallelism, stated between histoenzymatic and morphologic criteria of functional activity proved the participation of these structural-functional units in secret-producing processes. A high activity of NAK-diaphorase, LDG and acid phosphatase in all the parts and in the secreting ducts system, in particular, ensures, besides the processes of protein secret formation, an active transport of natrium and potassium, formation of final saliva and its discharge.     

Ultrastructural organization of polytene chromosomes of Chironomus thummi salivary glands]

An electronmicroscopical mapping of a number of regions of the polytene chromosomes of Ch. thummi salivary glands (3rd chromosome, right arm of the 1st chromosome, centromere regions, puffs 1-A2e, 1-A3ij, III-A5c and others) was done by the method of oriented ultrastructural sections of the unsquashed polytene chromosomes. The banding pattern on the electron micrograph was similar to the observed with the light microscope. The difference was that some doublets appeared as single cavity-containing bands with the double structure only in short regions under the electron microscope. It was also difficult to distinguish single bands in those regions where heavy adjacent bands were connected by dens, protrusions and anastomoses. These connections were most pronounced in the regions of the centromerers which had "spongy" appearance on the electron micrographs. These pictures may be connected with small interbands between heavy bands. Thin bands and some broad bands were frequently dotted. The puffs examined contained mainly RNP granules 200-400 A in diameter and RNP fibrils; BR-1 and BR-2 contained granules 500 A, RNP fibrils and smaller granules (200-400 A). BR and puffs were characterized by loop-like structures composed of granules arranged along the central DNP fibril. Only fibrils were presented in small interbands (0.05 mk), while larger interbands could include a small number of granules similar to those observed in puffs. It was found that centromere, telomeres and some heavy bands formed characteristic contacts with the nuclear membrane.     

Connexins in salivary glands

Connexins (Cxs) make up a family of gap junction structural proteins that form hexameric assemblies in the plasma membranes of adjacent cells that interact to form intercellular channels. It has been demonstrated that many kinds of CXs are differentially expressed in a variety of tissues; however, there have been only a few studies of CX expression in rat salivary glands. The co-localization of CX26 and 32 was examined in the parotid glands. Double immunofluorescence revealed that CX26 and 32 were present in the same gap junction. Double immuno-electron microscopy showed co-localization of both CX26 and 32 on the same gap junctional membranes between acinar cells. These results suggest that CX26 and 32 may participate in regulation of secretory function and permeability of acinar cells in the rat parotid glands.     

Morphology, histology and histochemistry of the ventral buccal salivary glands of the Arabian camel (Camelus dromedarius)

Morphometric, histological and histochemical investigations were carried out on the ventral buccal salivary glands of the Arabian camel ( Camelus dromedarius ). The ventral part (inferior molar gland) is composed of serous acini with abundant myoepithelial cells and the dorsal part of the gland comprises mucoserous acini. The serous acini are devoid of any type of mucosubstances while the mucoserous cells of the dorsal part show neutral glycoproteins and sialomucins but neither glycogen nor sulfomucins. The histoenzymological tests employed have detected alkaline phosphatase, adenosine triphosphatase, succinic dehydrogenase, non-specific esterases and α-amylase but no activities for aminopeptidase, lipase, cholinesterases and β-glucuronidase.     

Secretory and immunocompetent functions of the parotid and submaxillary salivary glands after thymectomy]

The dynamics of morphological, enzymatic and immunologic salivary glands indices in pubertal rates was investigated after thymectomy. The data obtained analysis demonstrated the functional salivary glands reconstruction, having immunologic and secretory characteristics: stimulation of the humoral and cellular immunity factors; reduction of the albuminous and rise of the mucous salivary glands component represented the remote effect of thymectomy /3 months]. Activation of the salivary glands immune characteristics may be explained by their belonging to the thymic-peripharyngeal complex.     

Channels and transporters in salivary glands

According to the two-stage hypothesis, primary saliva, a NaCl-rich plasma-like isotonic fluid is secreted by salivary acinar cells and its ionic composition becomes modified in the duct sytem. The ducts secrete K⁺ and HCO₃^- and reabsorb Na⁺ and Cl^- without any water movement, thus establishing a hypotonic final saliva. Salivary secretion depends on the coordinated action of several channels and transporters localized in the apical and basolateral membrane of acinar and duct cells. Early functional studies in perfused glands, followed by the molecular cloning of several transport proteins and the subsequent analysis of mutant mice, have greatly contributed to our understanding of salivary fluid and the electrolyte secretion process. With a few exceptions, most of the key channels and transporters involved in salivary secretion have now been identified and characterized. However, the picture that has emerged from all these studies is one of a complex molecular network characterized by redundancy for several transport proteins, compensatory mechanisms, and adaptive changes in health and disease. Current research is directed to the molecular interactions between the determinants and the ways in which they are regulated by extracellular signals and intracellular mediators. This review focuses on the functionally and molecularly best-characterized channels and transporters that are considered to be involved in transepithelial fluid and electrolyte transport in salivary glands.     

Aquaporins in salivary glands and pancreas

Background

Salivary glands and pancreas are involved in saliva secretion, pancreatic fluid secretion and insulin secretion. These functions are essential for proper oral, pancreatic and glucose homeostasis. Aquaporins are water-permeable transmembrane protein involved in the physiology of these secretory gland functions.

Scope of review

This review gives an overview of the morphology of salivary glands and pancreas, the expression and localization of aquaporins, the secretion roles and mechanisms, the physiological roles of aquaporins, and the role of aquaporins in pathophysiological conditions.

Major conclusions

Several aquaporins are expressed in salivary glands and pancreas, and some play important physiological roles. Modulation of aquaporin expression and/or trafficking may contribute to the pathogenesis of diseases affecting salivary glands and pancreas glands such as xerostomic conditions, pancreatic insufficiencies and diabetes.

General significance

Aquaporins are involved in physiological and pathophysiological processes in salivary glands and pancreas. They could represent therapeutic targets for the treatment of diseases affecting the salivary glands and pancreas. This article is part of a Special Issue entitled Aquaporins.     

Note on rhinoceros salivary glands

Limited observations are submitted upon the anatomy of the hitherto undescribed salivary gland formations in the rhinoceros genera Rhinoceros, Diceros and Ceratotherium.     

Histochemical characteristics of the lingual salivary glands of several classes of vertebrates]

The obtained results show that secretory elements of the tongue integuments submerged to the depth of the organ. It was accompanied by a formation and complication of terminal portions of the glands and their secretory pathways. In the process of evolution there occurred a divergence in the development of glandular cells from mucous ones in fishes through mucoserous and seromucous cells of amphibia and reptiles to mucous, seromucous and protein cells in the tongue glands of higher mammals. In mucous glands of terranian vertebrates, especially in mammals, the number of components in the composition of the produced secretion was found to increase.     

Organ culture of ixodid-tick salivary glands

This work describes an organ-culture method for isolated salivary glands of the ixodid tickAmblyomma hebraeum Koch. The support medium is a TC 199-1% agarose gel with no hormonal or undefined supplements. I used a fluid-transport assay for measuring viability of salivary glands. When cultured at 26°C, female glands secreted fluid at 65% on day 2,59% on day 4 and 42% on day 6 post-culture compared to glands tested on day 0. Fluid secretory rates in culture were higher than rates of glands from partially fed ticks (about 180–250 mg) on days 2, 4 or 6 post-removal from the host. Salivary glands from fed males cultured for 4 days lost only 5% of their fluid secretory competence, whereas glands dissected from males 4 days post-removal lost 63% of their fluid secretory competence.