A Correlated Thin Section and Freeze-Fracture Study of o-Phenylphenol-Induced Alterations in the Rat Liver

Pathobiology ◽  
1980 ◽  
Vol 48 (6) ◽  
pp. 404-420 ◽  
Author(s):  
Horst Robenek ◽  
Rüdiger Meiss ◽  
Hermann Themann ◽  
Sabine Himmeh
Keyword(s):  
Thin Section ◽  
Rat Liver ◽  
Freeze Fracture ◽  
Fracture Study

scholarly journals A thin-section and freeze-fracture study of microfilament-membrane attachments in choroid plexus and intestinal microvilli.

1978 ◽  
Vol 79 (3) ◽  
pp. 774-787 ◽  
Author(s):  
N S McNutt
Keyword(s):  
Choroid Plexus ◽  
Thin Section ◽  
Brush Border ◽  
Freeze Fracture ◽  
Similar Type ◽  
Heavy Meromyosin ◽  
Thin Sections ◽  
Intestinal Brush Border ◽  
Fracture Study ◽  
20 Nm

Choroid plexus and intestinal microvilli in thin sections have microfilaments in the cytoplasm adjacent to the membranes, and in replicas have broken strands of filaments in both cytoplasm and on E faces of plasm membranes. The microfilaments contain actin as indicated by their binding of heavy meromyosin (HMM). In sections of choroid plexus, the microfilaments are 7-8 nm in diameter and form a loose meshwork which lies parallel to the membrane and which is connected to the membranes both by short, connecting filaments (8 times 30 nm) and dense globules (approximately 15-20 nm). The filamentous strands seen in replicas are approximately 8 nm in diameter. Because they are similar in diameter and are connected to the membrane, these filamentous strands seen in replicas apparently represent the connecting structures, portions of the microfilaments, or both. The filamentous strands attached to the membrane are usually associated with the E face and appear to be pulled through the P half-membrane. In replicas of intestinal brush border microvilli, the connecting strands attaching core microfilaments to the membrane are readily visualized. In contrast, regions of attachment of core microfilaments to dense material at the tips of microvilli are associated with few particles on P faces and with few filamentous strands on the E faces of the membranes. Freeze-fracture replicas suggest a morphologically similar type of connecting strand attachment for microfilament-membrane binding in both choroid plexus and intestinal microvilli, despite the lack of a prominent core bundle of microfilaments in choroid plexus microvilli.

Homocellular and heterocellular gap junctions in Limulus: A thin-section and freeze-fracture study

1973 ◽  
Vol 43 (3-4) ◽  
pp. 298-312 ◽  
Author(s):  
Ross G. Johnson ◽  
William S. Herman ◽  
Doris M. Preus
Keyword(s):  
Gap Junctions ◽  
Thin Section ◽  
Freeze Fracture ◽  
Fracture Study

Tight and gap junctions in the intestinal tract of tunicates (Urochordata): a freeze-fracture study

1986 ◽  
Vol 84 (1) ◽  
pp. 1-17
Author(s):  
N.J. Lane ◽  
R. Dallai ◽  
P. Burighel ◽  
G.B. Martinucci
Keyword(s):  
Gap Junctions ◽  
Tight Junctions ◽  
Thin Section ◽  
Intestinal Tract ◽  
Freeze Fracture ◽  
Intestinal Cells ◽  
Fracture Profile ◽  
Tracer Studies ◽  
Septate Junctions ◽  
Fracture Study

The intestinal tracts from seven different species of tunicates, some solitary, some colonial, were studied fine-structurally by freeze-fracture. These urochordates occupy an intermediate position phylogenetically between the vertebrates and the invertebrates. The various regions of their gut were isolated for examination and the junctional characteristics of each part investigated. All the species examined exhibited unequivocal vertebrate-like belts of tight-junctional networks at the luminal border of their intestinal cells. No septate junctions were observed. The tight junctions varied in the number of their component strands and the depth to which they extended basally, some becoming loose and fragmented towards that border. The junctions consisted of ridges or rows of intramembranous particles (IMPs) on the P face, with complementary, but offset, E face grooves into which IMPs sometimes fractured. Tracer studies show that punctate appositions, the thin-section correlate of these ridge/groove systems, are sites beyond which exogenous molecules do not penetrate. These junctions are therefore likely to represent permeability barriers as in the gut tract of higher chordates. Associated with these occluding zonular junctions are intermediate junctions, which exhibit no identifiable freeze-fracture profile, and macular gap junctions, characterized by a reduced intercellular cleft in thin section and by clustered arrays of P face particles in freeze-fractured replicas; these display complementary aggregates of E face pits. The diameters of these maculae are rarely very large, but in certain species (for example, Ciona), they are unusually small. In some tissues, notably those of Diplosoma and Botryllus, they are all of rather similar size, but very numerous. In yet others, such as Molgula, they are polygonal with angular outlines, as might be indicative of the uncoupled state. In many attributes, these various junctions are more similar to those found in the tissues of vertebrates, than to those in the invertebrates, which the adult zooid forms of these lowly chordates resemble anatomically.

scholarly journals Loss and reappearance of gap junctions in regenerating liver.

1978 ◽  
Vol 78 (2) ◽  
pp. 554-564 ◽  
Author(s):  
A G Yee ◽  
J P Revel
Keyword(s):  
Gap Junctions ◽  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Close Association ◽  
Freeze Fracture ◽  
Regenerating Liver ◽  
Bile Canaliculi ◽  
Zonulae Occludentes ◽  
Fracture Study

Changes in intercellular junctional morphology associated with rat liver regeneration were examined in a freeze-fracture study. After a two-thirds partial hepatectomy, both gap junctions and zonulae occludentes were drastically altered. Between 0 and 20 h after partial hepatectomy, the junctions appeared virtually unchanged. 28 h after partial hepatectomy, however, the large gap junctions usually located close to the bile canaliculi and the small gap junctions enmeshed within the strands of the zonulae occudentes completely disappeared. Although the zonulae occludentes bordering the bile canaliculi apparently remained intact, numerous strands could now be found oriented perpendicular to the canaliculi. In some instances, the membrane outside the canaliculi was extensively filled with isolated junctional strands, often forming very complex configurations. About 40 h after partial hepatectomy, very many small gap junctions reappeared in close association with the zonulae occludentes. Subsequently, gap junctions increased in size and decreased in number until about 48 h after partial hepatectomy when gap junctions were indistinguishable in size and number from those of control animals. The zonulae occludentes were again predominantly located around the canalicular margins. These studies provide further evidence for the growth of gap junctions by the accretion of particles and of small gap junctions to form large maculae.

Cell junctions in amphioxus (Cephalochordata): A thin section and freeze-fracture study

1987 ◽  
Vol 19 (3) ◽  
pp. 399-411 ◽  
Author(s):  
N.J. Lane ◽  
R. Dallai ◽  
G.B. Martinucci ◽  
P. Burighel
Keyword(s):  
Thin Section ◽  
Freeze Fracture ◽  
Cell Junctions ◽  
Fracture Study

scholarly journals Coalescence of microsomal vesicles from rat liver: a phenomenon occurring in parallel with enhancement of the glycosylation activity during incubation of stripped rough microsomes with GTP.

1980 ◽  
Vol 86 (1) ◽  
pp. 29-37 ◽  
Author(s):  
J Paiement ◽  
H Beaufay ◽  
D Godelaine
Keyword(s):  
Electron Microscopy ◽  
Thin Section ◽  
Rat Liver ◽  
Freeze Fracture ◽  
Endogenous Protein ◽  
Previously Treated ◽  
Nucleotide Sugars ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron

Rough microsomes from rat liver have been subjected to various treatments and incubated afterwards with UDP-N-acetyl-[14C]glucosamine and GDP-mannose in the presence of GTP (0.5 mM), or of other nucleotides. In agreement with earlier results from this laboratory, the preparations previously treated to strip off the ribosomes and incubated in the presence of GTP assembled dolichol-linked oligosaccharides and transferred these oligosaccharides to endogenous protein acceptors much more actively than untreated preparations, or stripped preparations incubated in the absence of GTP. Thin-section and freeze-fracture electron microscopy have revealed that pyrophosphate-treated preparations incubated with GTP are aggregated and contain numerous vesicles as large as 1-4 micrometer, or more. Such large vesicles were not present before incubation and thus were considered to have been formed through coalescence of regular-sized ones. Like glycosylation, the coalescence phenomenon depends upon the removal of ribosomes, because it occurred whether ribosomes had been stripped, at least partly, with pyrophosphate, KCl, or puromycin, but not when rough microsomes had been washed with 0.25 M sucrose or with KCl and MgCl2. Like glycosylation, it also depends on the addition of GTP and was not induced by ATP, UTP, CTP, and nonhydrolysable analogues of GTP. Rough microsomes coalesced, however, when pyrophosphate-treated preparations were incubated with GTP in the absence of nucleotide sugars, or in the presence f tunicamycin, indicating that the coalescence phenomenon does not result from the glycosylation of some membrane constituents.

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