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  • 1
    Electronic Resource
    Electronic Resource
    The effect of temperature elevation and feeding on the pancreas of Rana esculenta in late winter (1969)
    Springer
    Cell & tissue research 98 (1969), S. 1-8 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hibernating frogs (Rana esculenta) in late winter were subjected to a higher environmental temperature. In addition the animals were fed. Electronmicroscopical and biochemical methods were used to follow the changes in the pancreas under these circumstances. The frog pancreas in winter is characterized by a very low protein synthesizing capacity, while the Golgi system is an extremely compact structure, composed of a mass of small vesicles. A rise in the environmental temperature does not initiate protein synthesis. However, zymogen granules appear and the Golgi system becomes more differentiated. Under these conditions protein synthesis is not started until a few hours after feeding. This is not accompanied by striking structural changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344503
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  • 2
    Electronic Resource
    Electronic Resource
    Transport of glycoproteins in the mucous surface cells of the rat stomach (1975)
    Springer
    Journal of molecular histology 7 (1975), S. 511-513 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01003788
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructural and carbohydrate histochemical studies on the differentiation and renewal of mucous cells in the rat gastric fundus (1977)
    Springer
    Cell & tissue research 176 (1977), S. 445-462 
    Details
    ISSN: 1432-0878
    Keywords: Gastric mucous cells ; Differentiation ; 3H-thymidine incorporation ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Gastric surface mucous cells (SMC), mucous neck cells (MNC) and their undifferentiated and immature precursors were studied by light and electron microscopic histochemistry. The secretory granules of SMC were smaller, more electron dense and more reactive to PAS and its analogues than those of MNC. Alcian blue demonstrated that the mucus of SMC was acidic and that of MNC was neutral. The periodic acid —thiocarbohydrazide —silver proteinate method revealed the presence of carbohydrates in the Golgi apparatus, condensing vacuoles, secretory granules, apical vesicles and tubules and cell coat. Maturation of SMC during their migration towards the free surface was reflected by an increase in size and number of secretory granules, an increase of RER and microfilaments, and a decrease of microvilli and apical vesicles and tubules. The secretory granules of older SMC were less acidic and possessed a proteinaceous core. Most MNC were fully differentiated, but some immature MNC containing only a few granules were found. Furthermore, undifferentiated cells and intermediates between SMC and MNC were also observed. The presence of both transitional and intermediate forms indicates that both SMC and MNC arise from the same population of undifferentiated cells. Incorporation of 3H-thymidine revealed that undifferentiated cells, isthmic SMC, MNC and intermediate cells are proliferative. No proliferative activity was found in foveolar SMC, parietal, chief, fibrillovesicular or endocrine cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231401
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  • 4
    Electronic Resource
    Electronic Resource
    Function of coated membranes and multivesicular bodies during membrane regulation in stimulated exocrine pancreas cells (1974)
    Springer
    Cell & tissue research 156 (1974), S. 1-20 
    Details
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Cell membrane regulation ; Coated vesicles, Multivesicular bodies ; Endocytosis ; Autoradiography, Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Stimulation of secretion by pilocarpine results in a 70% loss of zymogen granules from pancreatic acinar cell during the first hr after injection of the drug. In previous work (Geuze and Poort, 1973), we found that the amount of membrane stored in the surface of the microvilli and of the numerous infoldings present in highly stimulated cells, increases during the first 2 hr and then decreases again during the 3rd hr after stimulation, concurrently with maximal endocytosis of sorbitol-[su14C]. Further observations on the fine structure of stimulated cells at various time intervals after injection of pilocarpine showed that during the first hr numerous smooth vesicles and multivesicular bodies (mvb's) appear in the apical cytoplasm, while the number of coated vesicles and their relative total volume increase significantly 3 hr after stimulation. By infusion of ferritin in the pancreatic duct system in vivo and application of cytochemical techniques (osmium impregnation, electron microscope autoradiography and acid phosphatase cytochemistry) it could be established that after stimulated exocytotic secretion, redundant apical cell membrane is withdrawn by at least two routes: 1) During the initial rapid increase of the amount of apical cell membrane, withdrawal is accomplished by interiorization of luminal invaginations into smooth endocytotic vesicles, which in turn give rise to mvb's by infolding and subsequent fission of their limiting membrane. 2) Once the bulk of stored secretion granules has been discharged, endocytotic coated vesicles become gradually more prominent as carriers for redundant cell membrane. The contents of endocytotic structures ultimately become incorporated in residual bodies, suggesting lysosomal degradation of cell membrane prior to eventual reutilization. Coated vesicles also originate by pinching off from mature Golgi cisternae and condensing vacuoles. A possible function of the coated membranes in the concentration of exportable protein within forming secretory granules is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220098
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  • 5
    Electronic Resource
    Electronic Resource
    The cells of the rat gastric groove and cardia (1978)
    Springer
    Cell & tissue research 186 (1978), S. 375-391 
    Details
    ISSN: 1432-0878
    Keywords: Gastric mucous cells (rat) ; Cardia ; Fibrillovesicular cells ; Gastric groove ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distal wall of the groove between the rat forestomach and glandular stomach is lined with a special type of columnar cells (CCGG) and with fibrillovesicular cells (FVC). The cardiac glands contain cardiac mucous (CMC) and serous cells (CSC). The CCGG contain small mucous granules and special vesicles and tubules. The CMC are filled with large mucous granules and resemble mucous neck cells. The CSC are filled with large proteinaceous granules. The FVC are characterized by long microvilli, apical bundles of microfilaments and a complex “tubulovesicular system”. The pattern of 3H-thymidine incorporation and the presence of immature and transitional forms indicate a possible origin of all the cell types concerned from a common undifferentiated precursor. The membranes of the tubulovesicular system of FVC as well as the apical cell membrane were reactive to Thiéry's carbohydrate stain. However, lanthanum tracing of the extracellular space and ultrastructural stereoscopy did not reveal a permanent continuity between both membrane systems. The absence of 3H-thymidine label showed that FVC were not proliferative. The structural characteristics of FVC do not account for a secretory, resorptive or receptive function. The special arrangement of microfilaments and the tubulovesicular system suggests an ability to fast changes in surface area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224928
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  • 6
    Electronic Resource
    Electronic Resource
    Light and electron microscope observations on the gastric mucosa of the frog (Rana esculenta) (1971)
    Springer
    Cell & tissue research 117 (1971), S. 103-117 
    Details
    ISSN: 1432-0878
    Keywords: Gastric mucosa epithelium ; Frog ; Hibernation ; Structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of the frog gastric and esophageal mucosa was studied in the course of a complete hibernation period and compared with that in summer frogs (see preceding article). It appeared that especially chief cells and parietal cells are liable to cytoplasmic remodelling. Thus, in chief cells the rough endoplasmic reticulum (RER) undergoes disorganization, the number of free ribosomes increases and the Golgi system becomes transformed into a compact vesicular structure. The number of pepsinogen granules in chief cells of late winter frogs is only 20% of that in frogs studied at the onset of hibernation. The loss of pepsinogen granules is at least partly due to autophagy. In addition, lysosomes are involved in focal degradation of the cytoplasm, which may ultimately result in complete degeneration of some chief cells. The presence of zymogen granules containing fibrocyte-like cells in the tunica propria proved heterophagocytosis by these cells. In parietal cells, the area occupied by smooth endoplasmic reticulum becomes reduced. The basal cytoplasm of both chief cells and parietal cells contains numerous lipid droplets, which, in contrast to those in summer frogs, are continuous with RER cisternae. The juxtaposition of lipid droplets and mitochondria seen in summer frogs is eventually lost in hibernating animals. Apart from the appearance of supra-nuclear lipid droplets, the mucous cells of the surface epithelium show no striking alterations. However, in the glandular pits both surface mucous cells and mucous neck cells contain less mucous granules than in summer frogs. The results are discussed in connection with parallel biochemical work and available literature, and in the light of our previous studies on the exocrine pancreas in hibernating frogs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331105
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and intracellular transport of proteins in the exocrine pancreas of the frog (Rana esculenta) (1974)
    Springer
    Cell & tissue research 155 (1974), S. 135-154 
    Details
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Frog ; Ultrastructure ; Intracellular transport ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The route by which secretory proteins are transported in the frog exocrine pancreas cell was investigated by an ultrastructural and electron microscope autoradiographic analysis of in vivo 3H-leucine labelled tissue. The ultrastructure of the cell is characteristic of serous epithelial cells and resembles that of mammalian exocrine pancreas cells very closely. Autoradiographic results revealed that the proteins, after being synthesized in the rough endoplasmic reticulum (RER), are transported through the Golgi cisternae to condensing vacuoles which subsequently change into secretory granules. The determination of the timing of this transport was complicated by a very slow turnover of leucine in the frog. Nevertheless, by a semi-quantitative approach, some time characteristics could be estimated: about 11 min after the onset of their synthesis the proteins enter the Golgi system, and about 25 min later the condensing vacuoles. Secretory granules become labelled between 60 and 120 min. These results are discussed, also in relation to the transport route and kinetics in mammalian tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221350
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  • 8
    Electronic Resource
    Electronic Resource
    Light and electron microscope observations on the gastric mucosa of the frog (Rana esculenta) (1971)
    Springer
    Cell & tissue research 117 (1971), S. 87-102 
    Details
    ISSN: 1432-0878
    Keywords: Gastric mucosa ; Frog ; Epithelium ; Cell types ; Normal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Preliminary to a study on ultrastructural alterations in the foregut epithelium of Rana esculenta during hibernation, the structure of the epithelium in normal summer frogs is described. The foregut can be divided into three parts: the oesophagus, the forestomach and the stomach. In the epithelium eight cell types could be discerned. Chief cells are found only in the oesophagus and forestomach; parietal cells are limited to the stomach; argentaffin cells are present in both stomach and forestomach; surface mucous cells line the walls of stomach and forestomach; goblet cells and ciliated cells constitute the surface epithelium of the oesophagus; and finally mucous neck cells and intermediate cells are present in the glands of all three zones. Like chief cells, parietal cells contain granules with a presumably proteinaceous content, and thus correspond to the oxynticopeptic cells described in previous histological studies on the amphibian gastric mucosa. All cell types contain lipid droplets. Especially in surface mucous cells and parietal cells, these droplets are extremely numerous. Their possible role is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331104
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and intracellular transport of proteins in the exocrine pancreas of the frog (Rana esculenta) (1976)
    Springer
    Cell & tissue research 167 (1976), S. 147-165 
    Details
    ISSN: 1432-0878
    Keywords: Frog exocrine pancreas ; In vitro ; Intracellular transport ; Temperature sensitivity ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Frog pancreatic tissue was pulse-labelled in vitro with 3H-leucine and protein transport was studied in exocrine cells by electron microscope autoradiography. The proteins appeared to be synthesized in the RER and transported to the secretory granules along a similar route and with the same velocity as previously described under in vitro conditions. Evidence was obtained for the involvement of the vesicular and tubular elements at the periphery of the Golgi system in transferring protein from the RER to the Golgi cisternae. Kinetics of the release of newly synthesized proteins from the RER and their appearance in the condensing vacuoles are discussed and related to results reported from other tissues. The transport velocity in this poikilothermic system was studied in relation to the incubation temperature and compared with results reported from its mammalian counterpart. At temperatures between 20 and 30° C intracellular protein transport occurs faster in the frog than in the Guinea pig pancreas. At higher temperature the transport process was severely disturbed in the frog.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224324
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  • 10
    Electronic Resource
    Electronic Resource
    Secretion in the rat coagulating gland (Anterior Prostate) after copulation (1977)
    Springer
    Cell & tissue research 181 (1977), S. 519-529 
    Details
    ISSN: 1432-0878
    Keywords: Rat prostate ; Copulation ; Secretion ; Cytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of copulation on the rat coagulating gland (anterior prostate) was studied. At 4 to 6 h after the beginning of copulation the coagulating glands of rats that had produced copulatory plugs were nearly empty of secretion. Ultrastructurally, the coagulating gland has large cisternae of rough endoplasmic reticulum (RER) and few condensing vacuoles or secretion granules. After copulation the number of secretion granules and the frequency of their expulsion into the lumen increased. Also in the lumen were “fragmentation” vesicles (50–100 nm diameter) that were bounded by a unit membrane and appeared to arise from microvilli. At 4, 6, and 7h after the beginning of copulation there was an increase in apical blebbing. Blebbing was found in both perfusion and immersion-fixed tissue. Also, after copulation there was an increase in “light cells” that were characterized by reduced RER cisternae, an electron lucent cytoplasm, and atrophic Golgi apparatus. The luminal ground substance, secretion granules, and some Golgi elements, contained polysaccharides as seen with the periodic acid-thiocarbohydrazide-silver proteinate method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221773
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