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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Medical electron microscopy 32 (1999), S. 105-113 
    ISSN: 1437-773X
    Schlagwort(e): Key words Colon ; Large intestinal villi ; Absorptive cells ; Neonatal ; suckling rats ; Endocytosis ; Differentiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Cellular differentiation of the absorptive cells in the neonatal–suckling rat colon was investigated using horseradish peroxidase as a macromolecular tracer with a scanning or transmission electron microscope. Numerous villi were lined on oblique folds in an orderly fashion and smaller villi were lined between the folds in the proximal colon in 0- to 12-day-old rats. Three different types of absorptive cells were observed in the epithelium covering their villi: type I cells, type II cells, and type III cells. The type I cells were most numerous, and similar to typical absorptive cells of the adult rat large intestine. The type II cells endocytosed macromolecules into an apical endocytic membrane system without giant lysosome from the large intestinal lumen. The type III cells were characteristic of the well-developed endocytic membrane system, including a large supranuclear giant lysosome specialized for endocytosis, storage, and intracellular digestion as an ileal absorptive cell of the suckling rat. At no time was macromolecular tracer detected in the Golgi apparatus of the absorptive cells or in the intercellular space of the epithelium. These results suggest that the villial absorptive cells of the proximal colon have differentiated to three types at specific neonatal–suckling times. The type II and type III cells were not observed in the epithelium after the disappearance of the villi.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 251 (1988), S. 547-553 
    ISSN: 1432-0878
    Schlagwort(e): Oral mucosa ; Microridges ; Mucous secretion ; Fine structure ; Carp, Cyprinus carpio
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The surface of carp oral mucosa is characterized by various patterns of microridges about 0.3 μm wide, 0.1 μm high, and of various lengths. To elucidate the derivation and function of these microridges, the oral epithelium was examined by light- and electron microscopy. Microridges were present only on the surfaces of the superficial cells. Therefore, microridges on renewed superficial cells are presumed to be formed after old superficial cells have been discarded, and the various patterns of microridges found on the cell surface appear to indicate the progress of their development. In thin sections, the outer leaflet of the plasma membranes of microridges stained strongly with ruthenium red, and the underlying cytoplasm was packed with many fine filaments. The superficial cells contained many secretory vesicles that were PAS-positive but Alcian blue-negative at pH 2.5 and pH 1.0. However, after sulfation the vesicles gave a positive reaction with toluidine blue. These vesicles are secreted by exocytosis at the free surface of the cells. After release, the membranes of the vesicles are thought to be utilized for formation of microridges. On the basis of these observations, the possible function of microridges is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 276 (1994), S. 45-50 
    ISSN: 1432-0878
    Schlagwort(e): Oral mucosa ; Microridges ; Mucous secretory granules ; Coated vesicles ; Cytoskeleton ; Intracellular transport ; Cyprinus carpio (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Superficial cells of the oral mucosal epithelium in the carp and the cytoskeleton of the epithelial cells are examined by scanning and transmission electron microscopy. Microridges are formed on the surface of the epithelium. Epithelial cells contain two types of vesicles: mucous secretory vesicles and coated vesicles. Most of the mucous vesicles are situated in the center of the cell near the Golgi apparatus. In freeze-fracture replicas, intramembranous particles are abundant in the membranes of the secretory vesicles but rare in the apical plasma membrane. Coated vesicles are situated in the apical and subapical cytoplasm. A great number of thick filaments, considered to be keratin filaments, run randomly throughout the cell to form a meshwork. Thick filaments, which are sparse in the central cytoplasm, are connected to the membranes of the secretory vesicles and other membranous organelles. A layer of closely packed thin filaments, considered to be actin filaments, is found just beneath the apical plasma membrane. Microtubules also occur in the apical cytoplasm and run almost parallel to the cell surface. Both kinds of vesicles are connected to the thin and thick filaments. Their functional significance in the regulation of membrane at the free surface is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 261 (1990), S. 419-422 
    ISSN: 1432-0878
    Schlagwort(e): Oral mucosa ; Microridges ; Actin filaments ; Tight junctions ; Cyprinus carpio (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Actin filaments in the microridges on the surface of the fish oral mucosa taken from Cyprinus carpio were examined by electron microscopy after detergent extraction and decoration with myosin subfragment 1. After extraction with saponin, an irregular and densely packed meshwork of actin filaments was observed in the bases of the microridges, just lateral to the tight junctions with their fibrous undercoats. Actin filaments formed cores in the microridges and numerous linkages were seen between the filaments and the plasma membrane. Extraction with Triton X-100 and decoration with myosin subfragment 1 showed the ends of the actin filaments to be associated with the plasma membrane of the microridges, and in the bases of microridges the filament ends were anchored to intermediate filaments. Some actin filaments interconnected with the fibrous undercoats of the tight junctions. On the basis of these observations, the mechanism of the formation of microridges, including their pattern, is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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