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  • 1
    Electronic Resource
    Electronic Resource
    Intercellular junctions in the full term human placenta (1980)
    Springer
    Anatomy and embryology 158 (1980), S. 167-178 
    Details
    ISSN: 1432-0568
    Keywords: Placenta (human) ; Villous stroma ; Intercellular junctions ; Endothelium ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intercellular junctions within the villous stroma and the cytotrophoblastic layer of the human full term placenta were investigated using thin sectioning and freeze-fracturing. Numerous maculae adherentes (desmosomes) were found between the cytotrophoblast cells and the syncytiotrophoblast. This junction type was also seen connecting adjacent cytotrophoblast cells. Large gap junctions were frequently observed in contact areas of perikarya or at processes of adjacent fibroblasts. They often exhibited a peculiar pattern of their particles on the P-face of the membrane. Small rows of junctional particles were found on the P-faces of interconnected smooth muscle cells and gap junctions frequently bridged myoendothelial and interendothelial contact zones. The significance of the junctional complexes is discussed in relation to functional systems within the villous stroma of the human full term placenta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315904
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  • 2
    Electronic Resource
    Electronic Resource
    On the developing rat placenta (1980)
    Springer
    Anatomy and embryology 159 (1980), S. 289-305 
    Details
    ISSN: 1432-0568
    Keywords: Placenta (rat) ; Development ; Intercellular junctions ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The differentiation of chorionic layers II and III and alterations of intercellular junctions within the developing placental labyrinth were investigated in rats. Between the 14th and 16th day of gestation, the trabecular structures of the labyrinth alter and increasing numbers of primary, secondary, and tertiary lamellae develop. Trophoblastic layer I remains multicellular. Layer III rearranges and cytoplasmic fusions result in a continuous cytoplasmic barrier intervening between the already syncytial trophoblastic layer II and fetal capillaries. Simultaneously, most of the “undifferentiated” cells within the labyrinth disappear. Thin sectioning anf freeze-fracturing reveal multiple images of intercellular junctions, particularly gap and tight junctions in the cellular and syncytial parts of layers II and III. Continuous and regularly arranged tight junctions occur as well as fragmented structures which are spaced irregularly. Gap junctions are occasionally found between the juxtasinusoidal regions of layers II and III on the 14th day. More often they occur within restricted areas near the center of the trabeculae, integrated within extensive tight junctional strands. Gap junctions increase in later stages of pregnancy and eventually become distributed between the interfaces of layers II and III in the primary lamellae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317652
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastruktur des proximalen Nierentubulus nach Behandlung mit einem Pentosanschwefelsäureester (1974)
    Springer
    Research in experimental medicine 164 (1974), S. 19-33 
    Details
    ISSN: 1433-8580
    Keywords: Kidney ; Rat ; Ultrastructure ; Proximal tubule degeneration ; Heparinoid ; Niere ; Ratte ; Ultrastruktur ; Proximale Tubulusdegeneration ; Heparinoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 24 Std nach i.v. Injektion von 100 mg/kg eines Pentosanschwefelsäureesters (SP 54) sind in der Nierenrinde von Ratten schwere degenerative Veränderungen der proximalen Tubuluszellen zu beobachten. Das Tubulusepithel ist flachkubisch umgewandelt, das Tubuluslumen ist angefüllt mit ausgestoßenen Mitochondrien und anderen Zelltrümmern. Am stärksten betroffen ist die Pars contorta des proximalen Tubulus. Weniger stark veränderte Tubuluszellen sind angefüllt mit Cytosomen, die eine spezifische Feinstruktur haben oder gehäuft gegenüber Kontrollen Cytoplasmaprotrusionen in das Tubuluslumen aufweisen. Die akute Tubulusdegeneration ist ein spezifischer Effekt von SP 54. Heparin bewirkt nur eine leichte Schwellung des Tubulusepithels, die häufiger auftritt als bei Kontrolltieren.
    Notes: Summary 24 hrs after the intravenous injection of 100 mg/kg of a Pentosansulfuricacidester (SP 54) severe degenerative alterations are observed in the proximal tubular cells in rat kidney cortex. The tubular epithelium has changed to a single layer of elongated cubic cells. The tubular lumen is filled with cellular debris and extruded mitochondria. The greatest change is seen in the pars contorta of the proximal tubule. Less degenerated tubular cells have a great number of cytosomes with a specific substructure or have cytoplasmatic protrusions into the tubular lumen. This acute tubular degeneration is a specific event after the administration of SP 54 and is not seen after an equimolar dosis of Heparin. Heparin induces only a slight swelling of the tubular epithelium, more frequent seen as in the control animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01851961
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  • 4
    Electronic Resource
    Electronic Resource
    Morphological alterations and functional changes of interhepatocellular junctions induced by bile duct ligation (1977)
    Springer
    Cell & tissue research 182 (1977), S. 299-310 
    Details
    ISSN: 1432-0878
    Keywords: Liver ; Bile duct ligation (rat) ; Cell membrane ; Intercellular junctions ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of bile duct ligation on the intercellular junctions of hepatocytes was investigated. The features and the arrangement of the bile canaliculi and the zonulae occludentes alter concomitant to the increase of the intracanalicular pressure. The lumen of the bile canaliculi enlarges and the microvilli disappear. The array of the zonulae occludentes becomes irregularly shaped, the number of strands diminishes and interruptions of the strands occur. With peroxidase a leakage in the bile-blood barrier is detected. Furthermore a disappearance of gap junctions between the hepatocytes after bile duct ligation is observed. The present investigation shows that the zonulae occludentes are mobile structures which are changed by increased unilateral pressure. Due to their ultrastructural alterations, a leakage of the permeability barrier between physiological compartments is found. We acknowledge the helpful criticism and discussion of Prof. H.D. Fahimi. We are indebted to Mrs. B. Brühl, M. Bürkle and Ch. Walenta for technical assistance, and to stud. med. Jon Greenberg for preparing the manuscript
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219766
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  • 5
    Electronic Resource
    Electronic Resource
    Reformation of gap and tight junctions in regenerating liver after cholestasis (1979)
    Springer
    Cell & tissue research 199 (1979), S. 257-270 
    Details
    ISSN: 1432-0878
    Keywords: Liver ; Bile duct ligation ; Tight junctions ; Gap junctions ; Ultrastructure ; Freeze-fracturing ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphometric analysis of the alterations in interhepatocyte junctions induced by bile duct ligation revealed that after 48 h, during which time the serum bilirubin increased 6 to 8 fold, the membrane area occupied by gap junctions on the apico-lateral and medio-lateral sides decreased from 3.6% in controls to 0.02% in the ligated group. The strands of the zonulae occludentes were reduced in number and showed increased discontinuities. Within 45 min of recanalization of the common bile duct, clusters of particles appeared within and adjacent to the tight junctional areas or in the lateral hepatocyte membrane. Subsequently, the particle aggregations localized in the apico-lateral membrane areas increased in number and size becoming finally indistinguishable from those of controls within 96 h after the onset of recanalization. The zonulae occludentes also rearranged and reestablished their original structure during this period. The serum bilirubin fell to normal within 24 h of recanalization. It is concluded that metabolic and ultrastructural restitution associated with the recanalization of the ligated bile duct have no strict temporal correlation to one another. These studies provide further evidence that alterations in gap and tight junctions induced by pathological processes, e.g. during bile duct ligation, are completely reversible when regeneration occurs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236137
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  • 6
    Electronic Resource
    Electronic Resource
    Gap junctions in hemodichorial and hemotrichorial placentae (1976)
    Springer
    Cell & tissue research 171 (1976), S. 305-315 
    Details
    ISSN: 1432-0878
    Keywords: Chorioallantoic placenta ; Gap junctions ; Diaplacental transport ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Gap junctions were found to be a constant feature of chorioallantoic placentae with two or three trophoblastic layers. The gap junctions connect layers I and II in hemodichorial and layers II and III in hemotrichorial placentae. Although the gap junctions vary in form and in the packing density of membrane-associated particles, they cover an extensive surface area in all species examined. The gap junctions always connect adjacent membranes of two trophoblastic layers, which show no evidence of micropinocytotic activity; at least one of these trophoblastic layers is syncytial. It is therefore concluded that the gap junctions play an important role in diaplacental transport. We consider that gap junctions act as molecular sieves, resulting in limitations in the transport of large molecules. The passage of small molecules, on the contrary, would be facilitated by the gap junctions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224656
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  • 7
    Electronic Resource
    Electronic Resource
    Studies on the ultrastructure and permeability of the hemotrichorial placenta (1978)
    Springer
    Cell & tissue research 192 (1978), S. 391-407 
    Details
    ISSN: 1432-0878
    Keywords: Placenta (rat) ; Permeability ; Tracer ; Intercellular junctions ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of lanthanum chloride and horseradish peroxidase within the full-term chorioallantoic placenta of the rat was investigated 1 to 20 min after administration of these tracers into the maternal blood circulation. Both tracers rapidly penetrate trophoblastic layer I and diffuse into the interspace between layers I and II. They are localized in extensive infoldings and caveolae of the outer surface of layer II. The syncytial character of layer II is confirmed at this developmental stage of the placenta. There is no vesicular uptake or penetration beyond layer II until 20 min after tracer administration. Our results indicate that trophoblastic layer II is the main barrier in the chorioallantoic rat placenta preventing the permeation of macromolecules from maternal to fetal compartments. With freeze-fracturing, particulate structures of variable arrangement and size are found between adjacent cells of layer I. With goniometric analysis small gaps between the appositions of the membrane are observed. These structures are interpreted as tight and/or gap junctions during stages of assembly or disassembly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212321
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  • 8
    Electronic Resource
    Electronic Resource
    The use of ionic lanthanum as a diffusion tracer and as a marker of calcium binding sites (1977)
    Springer
    Cell & tissue research 178 (1977), S. 285-302 
    Details
    ISSN: 1432-0878
    Keywords: Rat heart ; Ultrastructure ; Excitation-contraction coupling ; Lanthanum chloride ; Calcium binding sites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of ionic lanthanum (La3+) was studied after perfusion of the isolated rat heart with a buffered salt solution containing lanthanum chloride. We have demonstrated that the localization of lanthanum differed from that shown in previous studies in which hearts were exposed to ionic or colloidal lanthanum during or after fixation. La3+ passed rapidly through the intercellular cleft between endothelial cells. There was relatively little transport by micropinocytosis and no evidence of transendothelial passage through the cytoplasm. Perfusion with a solution containing 1 to 15 mM LaCl3 resulted in localization of La3+ on the entire cytoplasmic membrane system of muscle cells, i.e.: the non-specialized parts of the muscle cell membranes were stained by La3+ as well as the membranes of micropinocytotic vesicles, of the T-system and of the intercalated disc. The cytoplasmic leaflets of gap junctions were especially stained. However, the cell membranes of non-muscle cells were free of lanthanum precipitates. Freeze-fracturing of muscle cells showed concomitant alteration in the distribution of membrane-associated particles. The gap junction membranes also showed changes in particle aggregation. Intracellular binding of La3+ was restricted to muscle cells. Lanthanum was found in the cell nucleus associated with heterochromatin, in the nucleolus, and along the nuclear membrane. The myofibrils were stained mainly over the I-band.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218693
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  • 9
    Electronic Resource
    Electronic Resource
    Exocrine pancreas under experimental conditions (1978)
    Springer
    Cell & tissue research 186 (1978), S. 227-240 
    Details
    ISSN: 1432-0878
    Keywords: Pancreas (rat) ; Pancreatic duct ligation ; Cell membrane ; Intercellular junctions ; Ultrastructure ; Freeze fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Exocrine pancreatic tissue was investigated during various intervals after pancreatic duct ligation. Concomitant to the increase of the intraluminal pressure, alterations are found in the arrangement of the luminal membrane surface and the zonulae occludentes of the acinar cells. The zonulae occludentes exhibit a disarrangement of their strands. The number of strands diminishes and small interruptions as well as large discontinuities of the strands are observed in most regions of the acinar cells. Furthermore, gap junctions are found very infrequently between acinar cells. The ultrastructural alterations of the zonulae occludentes suggest a gradual adaptation to the increasing unilateral pressure. However, a leakage of the paracellular permeability barrier occurs which contributes to the known shunt between the compartments of the pancreatic juice and the interstitial space following pancreatic duct obstruction. The present investigation is a further example of alterations in the paracellular permeability and intercellular communication of epithelial cells under pathological conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225533
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  • 10
    Electronic Resource
    Electronic Resource
    Studies on the ultrastructure and permeability of the hemotrichorial placenta (1978)
    Springer
    Cell & tissue research 192 (1978), S. 409-422 
    Details
    ISSN: 1432-0878
    Keywords: Placenta (rat) ; Capillary ; Permeability ; Tracer ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of horseradish peroxidase and lanthanum chloride within the full term chorioallantoic placenta of the rat was examined after administration of these tracers into the umbilical artery. Both tracers rapidly traverse the capillary endothelium. Transendothelial channels, fenestrations and micropinocytotic vesicles provide the main pathways. Intercellular clefts which are either patent or interrupted by leaky intercellular junctions, also contribute to a rapid passage of low and high molecular weight substances. Deep channel-like invaginations, effecting an increase of the exchange area of layer III, are freely accessible to the tracers from the interspace between the capillary endothelium and trophoblastic layer III. The invaginations, however, are not in continuity with the interspace between layers II and III, verifying the syncytial character of layer III. Neither an uptake of the tracers nor a passage across layer III is observed. The main permeability barrier to feto-maternal transfer within the chorioallantoic placenta is localized in the syncytiotrophoblastic layer III. This layer controls the passage of low molecular weight substances and restricts the penetration of high molecular weight substances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212322
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