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  • 1990-1994
  • 1975-1979  (3)
  • Epithelioid cells  (2)
  • Fine structure  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 202 (1979), S. 41-61 
    ISSN: 1432-0878
    Schlagwort(e): Abdominal muscle receptor organ ; Dendrites ; Fine structure ; Crayfish
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The structure of both the slow- and the fast-adapting abdominal muscle receptor organ of Astacus leptodactylus is described with particular reference to differences between the two systems. The receptors are composed of a thin muscle that extends from the front edge of one segment to the front edge of the following and a sensory cell connected with this muscle. In the zone where the sensory cells enter their respective muscle, muscle fibers are reduced (zone of relative muscle exclusion=ZRME) and partly replaced by connective tissue. The occurrence of dendritic processes of both the slow and the fast neurons is confined to this zone. The following differences between the two receptor types are established: (1) The fast receptor muscle reveals a smaller sarcomere length than the slow receptor muscle and a higher myosin/actin filament ratio. (2) Muscle fibers that pass the ZRME are always found at its periphery in the fast system, separated from dendritic processes by layers of connective tissue, while in the slow system muscle fibers frequently are intermingled with the sensory elements. (3) The ZRME of the slow receptor is 20–30% longer than that of the fast receptor. (4) The dendritic varicosities of the slow neuron, on an average, contain many more mitochondria than those of the fast neuron. (5) Dendritic processes (fine twigs as well as varicosities) are juxtaposed to the sarcolemma of the muscle fibers only in the slow system; in the fast system dendrites and muscle are spatially separated by connective tissue. It is assumed that these differences between the two receptor types arep at least in part responsible for the different thresholds observed in physiological experiments.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0878
    Schlagwort(e): Peroxidatic activity ; Monocytes ; Macrophages ; Epithelioid cells ; Multinucleated giant cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The peroxidatic (PO) activity of monocytes differentiating into macrophages, epithelioid cells, and multinucleated giant cells in subcutaneous granulomas was investigated with three different media for the demonstration of PO activity. Irrespective of the stage of differentiation, these cells did not show PO activity in the rough endoplasmic reticulum (RER) or nuclear envelope. In addition, it was found that the morphologically characteristic types of granule of the various cells of the monocyte line (the primary granules and secondary granules of monocytes, the macrophage granules, and the epithelioid cell granules), all have distinct cytochemical characteristics. Monocytes lose their primary and secondary granules during differentiation into mature macrophages. Simultaneously, the granules of both types become elongated and the secondary granules lose their halo. In contrast to monocytes, mature macrophages may contain a few microperoxisomes. During the differentiation of macrophages into epithelioid cells or multinucleated giant cells there is an increase in the number of microperoxisomes.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-0878
    Schlagwort(e): Monocytes ; Macrophages ; Epithelioid cells ; Multinucleated giant cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The morphological changes occurring in monocytes during their differentiation into macrophages, epithelioid cells, Langhans-type giant cells, and foreign-body-type giant cells were investigated in foreign-body granulomas induced by subcutaneous implantation of pieces of Melinex plastic. Analysis based on Adams's (1974) criteria for discrimination between the several types of cell of the monocyte line, showed that each type has a characteristic type of granule. Primary and secondary granules, numerous in the Golgi area of monocytes were generally found close to the cell membrane and decreased in number in maturing macrophages. This was accompanied by an increase in the number of microtubules. Mature macrophages show numerous characteristic macrophage granules, which are round (average diameter: 280 nm) and have a halo between the limiting membrane and granular matrix. Mature epithelioid cells have characteristic epithelioid cell granules, and multinucleated giant cells a heterogeneous population of granules. Fusing macrophages generally have their Golgi areas facing each other, and also show a reduced thickness of the cell coat. The morphology of the multinucleated giant cell is closely related to the number of nuclei present. In Langhans-type giant cells, which generally have two to ten nuclei, a giant centrosphere with numerous aggregated centrioles is found. In transition forms between Langhans-type and foreign-body-type giant cells, which generally contain 10–30 nuclei, the centrioles show less aggregation. In the foreign-body-type giant cells, which generally have more than 30 nuclei, centrioles are virtually absent and never aggregated. These differences between the Langhans-type giant cells, the foreign-body-type giant cells, and the transition forms, support our previous finding that Langhans-type giant cells are the precursors of foreign-body-type giant cells.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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