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  • Life and Medical Sciences  (3)
  • Small intestine  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Macromolecules can pass through occluding junctions of rat ileal epithelium during cholinergic stimulation (1987)
    Springer
    Cell & tissue research 247 (1987), S. 547-554 
    Details
    ISSN: 1432-0878
    Keywords: Goblet cells ; Small intestine ; Tight junctions ; Peroxidase ; Cholinergic drugs ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Crypt, but not villus, goblet cells in the ileum accelerate their secretion of mucus within 5 min following cholinergic stimulation. This study was done to determine whether the macromolecular permeability and structure of occluding junctions in the ileum are altered during accelerated secretion. Rats were injected intravenously with horseradish peroxidase followed by carbachol (250 μg/kg, subcutaneous) and the intestinal mucosa was fixed 3–12 min later. In control mucosa (saline-injected), peroxidase filled lateral intercellular spaces up to the occluding junctions of both crypt and villus epithelium, but did not enter occluding junctions or pass into the lumen. In 3 of 8 carbachol-stimulated rats, peroxidase was present within occluding junctions in crypt epithelium and in the crypt lumen, although all intermembrane junctional fusion sites appeared intact. Villus epithelial occluding junctions, in contrast, continued to exclude peroxidase. In freeze-fracture replicas of crypt cells prepared after carbachol stimulation, we detected no structural changes in strand networks of occluding junctions that could account for increased paracellular permeability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215748
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Linear arrays of intramembrane particles on microvilli in primate large intestine (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 367-381 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Distinctive linear arrays of intramembrane particles were present in microvillar membranes of approximately 5% of surface columnar cells observed in freeze-fracture replicas of monkey colon and human rectum. On these cells, longitudinally-oriented rows of P face particles and corresponding E face grooves appeared on all exposed microvilli. The constituent particles varied from round (8-9 nm in diameter) to rod-shaped (18 nm long). Microvilli of the great majority of columnar cells displayed randomly distributed P face particles similar to those previously observed in small and large intestine of birds and small mammals. The significance of the linear arrays is not known. It is postulated that they may represent protein assemblies which are specific to a functionally-distinct subpopulation of primate intestinal columnar cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091930304
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Glycoconjugate distribution and mobility on apical membranes of absorptive cells of suckling rat ileum in vivo (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 213 (1985), S. 520-528 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The luminal membrane of ileal absorptive cells in suckling rats includes two domains: microvillar membranes and deep invaginations between microvilli. We examined the fates of foreign macromolecules that bind to anionic or saccharide sites on these domains after infusion into ligated loops in vivo. Cationized ferritin (CF) and ferritin-RCAI (β-galactosyl) binding sites were distributed over the entire apical membrane. Ligands bound to apical invaginations were rapidly endo cytosed, but ligands on microvilli were not. After CF binding, anionic sites on microvilli were mobile in the plane of the membrane and formed CF clusters at the tip and base of each microvillus. RCAI binding sites did not cluster. Wheat germ agglutinin (WGA, sialic acid) labeling was restricted to microvillus tips of mature cells but was dispersed over the microvillar surfaces of lower villus cells. Ferritin conjugates of Concanavalia ensiformis (Con A), Ulex europaeus agglutinin (UEA), and Dolichos biflorus agglutinin (DBA) did not bind to cell surfaces in vivo. Aldehyde fixation dramatically altered lectin binding patterns, resulting in unmasking and labeling of Con A, WGA, and DBA binding sites that were unavailable in vivo.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092130408
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The surface topography of the colonic crypt in rabbit and monkey (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 160 (1981), S. 461-472 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Scanning electron microscopy (SEM) was used to investigate the epithelial topography of the surface and crypt in rabbit and monkey colon. Crypt openings in monkey colon are arranged in a hexagonal pattern, in sharp contrast to rabbit colon where they are randomly arrayed and frequently hidden by epithelial folds. Crypt lumens were exposed by freezing ethanol-dehydrated tissue in liquid nitrogen and fracturing the tissue with a razor blade. The resulting overview of crypt-cell luminal surfaces showed that as columnar cells mature and migrate up the crypt and onto the colonic surface, their microvilli become progressively more abundant. Goblet cells were readily identified in the cross-fractured crypt epithelium; their luminal surfaces are characterized by short, sparse microvilli. The changing appearance of the luminal surface of goblet cells was visualized by SEM during the exocytosis of single mucous granules from unstimulated crypt goblet cells, and during the compound exocytosis of multiple granules in response to acetylcholine.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001600409
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    Paper (German National Licenses)
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