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  • 1
    Electronic Resource
    Electronic Resource
    Collagen Resorptlon in the Gingiva of the Mouse Incisor (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of clinical periodontology 7 (1980), S. 0 
    Details
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-051X.1980.tb01989.x
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  • 2
    Electronic Resource
    Electronic Resource
    Quantitative analysis of connective tissue resorption in the supra-alveolar region of the mouse incisor ligament (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 17 (1982), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: During eruption of the mouse incisor part of the periodontal ligament moves along with the tooth in the occlusal direction and is degraded in the supra-alveolar region.In the present study stereologic analysis at the ultrastructural level has shown that significant reduction of the amount of extracellular collagen is confined to the most occlusal region of the ligament, just apically to the functional epithelium. In connection herewith a relatively high amount of homogeneous material of moderate electron density was found in the intercellular space, suggesting a process of extracellular collagen breakdown near the epithelium-connective tissue interface.With respect to the distribution of collagen phagocytosis by fibroblasts, it appeared that the volume density of cytoplasmic vacuoles containing collagen fibrils was considerably higher in the supra-alveolar region of the ligament than in its subcrestal part, particularly in the zone along the tooth surface. This phenomenon is interpreted as being indicative of increased phagocytic activity of fibroblasts leading to the detachment of the periodontal ligament from the cemeatum before it enters the region of final degradation near the apical termination of the junctional epithelium.In an attempt to identify the cells involved in the degradation of (fragments of) periodontal fibroblasts in the supra-alveolar region, periodontal ligament cells were labelled with tritiated thymidine at their site of origin. By means of both autoradiography and electron microscopy, it was shown that, following the arrival of Jabelled fibroblasts in the supra-alveolar region, at least part of the degradation of cellular constituents is accomplished via a process of heterophagocytosis among fibroblasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1982.tb01171.x
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  • 3
    Electronic Resource
    Electronic Resource
    Electron microscopy of formation of statoconia (1969)
    Springer
    Cellular and molecular life sciences 25 (1969), S. 1173-1174 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Erstmaliger Nachweis der Kristallisationszentren in den Statolithen des Innenohrs 15 Tage alter Mäuseembryonen. Die primären Statokonien sind aus lockerer Grundsubstanz aufgebaut mit elektronendichten Körnchen von 20–60 å, die als erste Kalzitpräzipitate aufgefasst werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01900258
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  • 4
    Electronic Resource
    Electronic Resource
    X-ray microanalysis of colloidal-gold-labelled lysosomes in rat liver sinusoidal cells after incubation for acid phosphatase activity (1980)
    Springer
    Histochemistry and cell biology 66 (1980), S. 137-148 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lysosomal apparatus of the Kupffer and endothelial cells of the sinusoidal lining of the rat liver was found to take up colloidal-gold particles with a mean diameter of 5 nm, prepared according to a modified method. After incubation of the glutaraldehyde-perfusion-fixed tissue in a lead-containing medium for the demonstration of acid phosphatase activity, a reaction product was observed in the gold-loaded lysosomes. By X-ray microanalysis of such lysosomes, the presence of osmium, gold and lead was detected qualitatively in the unstained sections from the tissue, which after the incubation had been post-fixed with an OsO4-solution to which K4Fe(CN)6 had been added to enhance the contrast. The quantitative computer-assisted processing of the X-ray microanalytical data from such lysosomes enabled to determine the gold-to-lead ratio and the individual gold and lead peak intensities derived from both the Mα and Lα values in the spectra. On the basis of these results and those obtained similarly in control lysosomes containing either only gold or only lead phosphate precipitate, it was found that only the Lα values were reliable, whereas the Mα values from the same lysosomal spectra were unrealistic, due to deconvolution problems in the computer programs applied. Based upon the Lα values it was found that among the population of lysosomes in single Kupffer cells, studied after a 60-min interval between the injection of the gold colloid and fixation, three types of lysosomal contents could be quantitated by X-ray microanalysis, viz. one type with only gold, one with only lead, one with gold and lead, in various ratios. This quantitative approach might make it possible to detect variations in lysosomal composition associated with ageing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00494641
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  • 5
    Electronic Resource
    Electronic Resource
    Histochemical detection of glycogen phosphorylase activity as parameter for early ischemic damage in rat heart (1993)
    Springer
    Basic research in cardiology 88 (1993), S. 130-140 
    Details
    ISSN: 1435-1803
    Keywords: Ischemia ; myocytes ; enzyme histochemistry ; glycogen phosphorylase ; cytophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the present study we have investigated whether enzyme histochemical parameters can be applied to detect early ischemic damage in rat heart after ischemia without restoration of the blood flow. Ischemia was induced by incubating heart fragments for 0, 10, 20, 30, 60, 120 and 240 min at 37°C. The activity and localization of the following enzymes was studied in unfixed cryostat sections using quantitative histochemical methods: lactate dehydrogenase, creatine kinase, succinate dehydrogenase, phosphofructokinase, acid phosphatase, 5′-nucleotidase and glycogen phosphorylase. Moreover, the ultrastructure of the tissue was studied with special attention to the appearance of flocculent densities in mitochondria, which can be seen as a sign of irreversible cell damage. It was shown that glycogen phosphorylase activity in rat heart decreased after short periods (30 min) of in vitro ischemia, whereas all other enzymes studied were not decreased up to 240 min, with the exception of lactate dehydrogenase and phosphofructokinase activities which were diminished only at 240 and 120 min of ischemia, respectively. Some reaction product was found after incubating for 5′-nucleotidase activity in the absence of substrate, indicating the presence of endogenous substrate(s). This endogenous substrate disappeared from the myocytes after 20 min of ischemia. It is assumed that AMP and/or other phosphate-containing compounds play an essential role in the activation of glycogen phosphorylase. Significant reduction of glycogen phosphorylase activity is correlated with the irreversible stage of damage of myocytes as judged from the ultrastructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798261
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  • 6
    Electronic Resource
    Electronic Resource
    Resorption of connective tissue in the gingiva of the mouse incisor (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 95-107 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: During eruption of the mouse incisor part of the periodontal ligament moves along with the tooth in occlusal direction and is degraded in the gingiva, just apically of the junctional epithelium. When studied with the electron microscope some connective tissue cells (fibroblasts) showed disorganization of both nucleus and cytoplasm. In other cells vacuoles were observed containing partly degraded cellular constituents. Sometimes within these vacuoles electron dense material with the appearance of clumped chromatin was observed. On the basis of this observation it is concluded that heterophagocytosis contributes to the process of fibroblast breakdown. The ultrastructure of these heterophagic cells resembled that of fibroblasts.Collagenous fibrils were observed within cytoplasmic vacuoles of fibroblasts indicating that collagen is phagocytosed and probably digested in the lysosomal apparatus. Part of the intercellularspace was filled with a homogeneous material of moderate electron density, intermingled with some collagenous fibrils.Within some cells of the junctional epithelium partly degraded material was observed which may indicate that the epithelium contributes to the removal of residual products of connective tissue degradation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091950108
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  • 7
    Electronic Resource
    Electronic Resource
    Lysosomal breakdown of erythrocytes in the sheep placenta (1979)
    Springer
    Cell & tissue research 197 (1979), S. 79-94 
    Details
    ISSN: 1432-0878
    Keywords: Erythrophagocytosis ; Lysosomes ; Placenta (sheep) ; Acid phosphatase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The breakdown of erythrocytes within the lysosomal apparatus of trophoblastic epithelial cells of the sheep placenta was studied at the ultrastructural level. Acid phosphatase activity could be demonstrated in the interspace between the erythrocyte membrane and the lysosomal membrane, but not inside ingested erythrocytes. The erythrocyte plasma membrane remained observable until the final stage of the breakdown process. Together with a peripheral layer of indigestible hemoglobin it might form a barrier for further penetration of lysosomal enzymes into the ingested erythrocyte. The hemoglobin of the erythrocyte is suggested to diffuse through the erythrocyte plasma membrane into the interspace between this membrane and the lysosomal membrane. Subsequently, the hemoglobin is digested in the interspace or in fragments pinched off from erythrocyte-containing lysosomes (=erythrolysosomes). The fragmentation of erythrolysosomes is considered to be the most efficient mechanism for the breakdown of red blood cells in the trophoblastic epithelium of the sheep placenta. The method of entry of hydrolytic enzymes into erythrocyte-containing phagosomes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233555
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  • 8
    Electronic Resource
    Electronic Resource
    Ageing of mouse liver lysosomes (1974)
    Springer
    Cell & tissue research 155 (1974), S. 455-473 
    Details
    ISSN: 1432-0878
    Keywords: Lysosomes ; Liver ; Ageing ; Exocytosis ; Thorotrast ; Electron microscopy, Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Lysosomes in mouse liver parenchymal cells have been marked by intravenous injection of Thorotrast. They were subsequently followed in a time sequence from five hours up to sixteen weeks after injection. At two days after injection the majority of the lysosomes was heavily loaded with marker particles, while endocytosis was no longer observed. From six days after injection Thorotrast was partly accumulated in very large lysosomes (conglomerates) with mean diameters up to 2.5 μm. As the time after injection advanced the Thorotrast content of the cells was reduced while most of the remaining marker substance became concentrated in the conglomerates. Many Thorotrast conglomerates were shown to contain acid phosphatase and some of them were able to fuse with functionally younger lysosomes which were marked with colloidal gold. Morphometric analysis showed an increase in the volume density of the dense body population between 0 and 2 days after injection, followed by a decrease between 2 and 11 days. The observed decrease is probably caused by exocytosis of the contents of Thorotrast containing lysosomes in bile capillaries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227009
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  • 9
    Electronic Resource
    Electronic Resource
    Final stages of erythrophagocytosis in the sheep placenta (1981)
    Springer
    Cell & tissue research 214 (1981), S. 501-518 
    Details
    ISSN: 1432-0878
    Keywords: Placenta (sheep) ; Cell phagocytosis ; Hemoglobin-derived pigments ; Residual bodies ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In trophoblastic epithelial cells of the sheep placenta the final stages of erythrocyte breakdown within the lysosomal apparatus were studied at the ultrastructural level. As a result of hemoglobin digestion lysosomes containing hemoglobin-derived pigments (HDP) were formed. The HDP-lysosomes were acid phosphatase-positive, highly electron-dense bodies of round to irregular shape containing whorled membranous formations. The accumulation of these lysosomes in epithelial cells led to fusion resulting in the formation of conglomerates. At the end of the gestation period the amount of HD Plysosomes and their conglomerates markedly increased. In addition to erythrocytes the trophoblastic epithelial cells in the erythrophagocytic regions phagocytosed maternal leukocytes and neighbouring epithelial cells and giant cells. By gradual accumulation of HDP-lysosomes and remnants of phagocytosed cells, highly electron-dense acid phosphatase-positive residual bodies of variable appearance were formed within the epithelial cells. At the end of pregnancy the spaces between juxtaposed villi of the trophoblastic epithelium in the erythrophagocytic zones were occluded by apposition of the epithelial cells. In these occluded regions an increase in highly electron-dense large-sized residual bodies (15–22 μm of dimension) occurred as a result of multiple cell phagocytosis in combination with fusion. In these residual bodies the numerous incorporated HDP-lysosomes and the remnants of phagocytosed cells could still be recognized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233491
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  • 10
    Electronic Resource
    Electronic Resource
    Quantitative changes in the lysosomal vacuolar system of rat hepatocytes during short-term starvation (1986)
    Springer
    Cell & tissue research 243 (1986), S. 641-648 
    Details
    ISSN: 1432-0878
    Keywords: Hepatocytes ; Lysosomes ; Macroautophagy ; Microautophagy ; Starvation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural morphometric analysis was used to study time-dependent variations in macro and microautophagy in rat hepatocytes. Except during periods of shortterm starvation for up to 24 h, animals were kept under standardized conditions of food intake. In hepatocytes of meal-fed rats the volume fraction of macroautophagic vacuoles is significantly higher at 23:00 h, i.e., immediately before food intake, compared to 11:00 h, i.e., 12 h following feeding. During fasting, macroautophagy drops to a low level. Microautophagic vacuoles in hepatocytes of meal-fed rats, sacrificed at 11:00 or 23:00 h respectively, do not show any significant quantitative differences. However, during 12 h of starvation, the volume fraction of microautophagic vacuoles rises significantly, whereas the numerical density remains constant. Subsequently, during the second 12-h period of fasting, the volume fraction of microautophagic vacuoles remains unchanged, but the numerical density increases. Over a period of 24 h of starvation the volume fraction of the total lysosomal system does not change significantly, whereas the numerical density rises. The time-dependent changes of the macroautophagic vacuolar system correlate with the circadian, food-related variations in the protein content of individual hepatocytes from meal-fed animals. The increase in volume fraction and thereafter in number of microautophagic vacuoles, as observed during starvation, coincides with a large decrease in protein content of individual hepatocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218073
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