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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Journal of neurocytology 4 (1975), S. 697-712 
    ISSN: 1573-7381
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The innervated and noninnervated membranes ofTorpedo electrocytes have been examined by electron microscopy of thin-sectioned and freeze-fractured specimens. The ventral innervated membrane is ∼120 Å thick and is characterized by an unusually broad outer dense lamina (∼60 Å) in which a granular substructure can be resolved. The granules are ∼70 Å in diameter and are spaced irregularly. The same membrane specialization was noted in a previous study of amphibian myoneural junctions, and it was proposed then that the granular elements represent ACh receptor molecules. The morphologically equivalent structures presumably have the same significance in theTorpedo electric organ. However, in this case the specialized membrane covers the entire innervated surface, leading to the conclusion that high concentrations of receptors occur normally in extrajunctional as well as post-junctional regions of the innervated membrane of the electrocyte. In replicas of freeze-fractured specimens, the A face of this membrane is covered with large particles having the same distribution and approximate concentration as the granules visible in thin sections, indicating that the granules visible at the outer surface of the membrane extend at least into the hydrophobic middle layer of the membrane. The cytoplasmic surface of this membrane has an amorphous coating into which ‘decorated’ cytoplasmic filaments insert. Synaptic vesicle and axon terminal membranes also contain granules visible in thin sections but with a much sparser distribution. These probably correspond to the intramembranous particles seen in freeze-fractured specimens. Vesicles are occasionally attached. to the axolemma by thin linear strands.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 60 (1963), S. 213-236 
    ISSN: 1432-0878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. The neurons and glial cells of the visceral ganglion are closely packed together except in the peripheral zone of the ganglion, where an extracellular space, the subcapsular sinus, occurs. The interglial clefts are often dilated in this region, and contain small amounts of the flocculent material which fills the sinus. 2. Most of the glial cells of the peripheral zone are filled with particles of glycogen. Processes of these cells invaginate deeply into neuronal perikarya. Patches of glycogen also occur in the neurons. 3. Some of the neurons contain small, membrane-limited granules which resemble neurosecretory granules. These appear to arise in Golgi cisternae. Such granules also occur in neuronal processes within the basement membrane of the ganglion and in the connective tissue capsule outside. In the latter location the nerve fibers may be entirely unsheathed. 4. Small caliber processes in the neuropil contain vesicles which resemble synaptic vesicles in other locations. In this ganglion the vesicles usually have osmiophilic centers.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 215 (1986), S. 182-191 
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The structure of the satellite cell sheath of frog dorsal root ganglion cells was studied in thin sections and freeze-fracture replicas. The sheath around the cell body is composed of thin satellite cell lamellae closely applied to the neuronal plasma membrane. At the axon hillock the sheath divides into outer and inner components separated by a broad space containing a distinctive extracellular matrix and occasional flattened satellite cell processes. The sheath around the initial segment is usually multilayered but less compact than that around the cell body, and in some places it exhibits node-like interruptions. Apart from occasional particle groupings characteristic of tight junctions and gap junctions, the satellite cells display homogeneously distributed intramembranous particles in both fracture faces in all regions of the sheath.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 177 (1973), S. 1-13 
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: A population of catecholamine-containing subependymal cells bordering the preoptic recess of the toad hypothalamus was studied by the rapid Golgi method to determine whether the cells have the characteristic contours of neurons or are instead secretory cells similar to peripheral chromaffin cells as proposed in an earlier study. Golgi impregnations of these cells reveal that they possess long basal processes which extend toward the lateral surface of the brain and which are covered with clusters of short projections and longer single projections. The relatively large caliber and rough surface of these processes distinguish them from axonal processes of neurons. Instead the cells closely resemble the ependymal cells bordering the preoptic recess with respect to the lateral course of the basal processes and with respect to the projections on these processes. The only qualitative difference between the ependymal and subependymal cells seen in Golgi preparations is the presence of apical processes projecting from the subependymal cell bodies through the ependymal layer to border on the ventricle. On the basis of this and the earlier study it is concluded that the subependymal cells do not have the characteristics of neurons but instead constitute a new cell type similar to ependymal cells but specialized for the synthesis, storage and secretion of catecholamines.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 199 (1981), S. 267-279 
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: We have examined the ependymal astrocytes of the frog cerebellar cortex in thin sections and freeze-fracture replicas. The somata border the fourth ventricle and give rise to basal processes whose daughter branches cross the molecular layer and terminate as subpial endfeet. Irregular lamellar appendages arise from the basal processes and their branches. In the molecular layer the appendages selectively ensheath apposed parallel fiber boutons and Purkinje cell dendritic spines. Other appendages ramify throughout the neuropil, some contributing to extensive pericapillary sheaths.Freeze-fractured ependymal astrocyte plasma membrane consistently has a greater concentration of intramembranous particles (IMPs) and IMPs of larger mean size than neuronal plasma membrane in the same replicas. Like the astrocytes of the mammalian central nervous system, frog ependymal astrocytes form numerous gap junctions with each other. However, orthogonal arrays of IMPs (“assemblies”) were not observed.Ependymal cells in the frog cerebellum combine the morphology, and probably the functions, of both ependymal cells and astrocytes.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 204 (1982), S. 95-100 
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The binding of colloidal iron hydroxide (CI) and ruthenium red (RR) to the plasma membrane of frog ependymal astrocytes was examined by electron microscopy. Positively charged CI and RR bind to the external surface of the plasma membrane of all parts of the ependymal astrocyte. Prior treatment with neuraminidase markedly reduces the number of bound CI particles, suggesting that the sialic acid of carbohydrates associated with the cell surface is responsible for much of the CI binding. Comparable observations were made on mouse ependymal cells. These findings indicate that an anionic, carbohydrate-rich cell coat occurs on the plasma membrane of amphibian ependymal astrocytes and mammalian ependymal cells. This cell coat may be related to transport, barrier, or receptive functions of ependymal cells.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 229 (1991), S. 138-143 
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Minced and triturated fragments from the spinal cord of normal rat fetuses (15-18 days gestation) labeled with the fluorescent dye fast blue (FB) were successfully transplanted into juvenile myelin-deficient rat spinal cord under direct observation. Clusters of myelinated fibers were found subsequently in the recipient spinal cord, and, by fluorescence microscopy, clusters of FB-labeled cells were found at corresponding sites. The results indicate that the surgical approach used is suitable for transplantation of tissue fragments into a defined region of juvenile rat spinal cord, that FB can be used to locate the transplanted cells subsequently, and that FB does not interfere with maturation of the donor glia or with myelin formation.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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