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  • Hamster  (2)
  • Polytoma  (2)
  • Axon-sprouting  (1)
  • Chloride channels  (1)
  • Springer  (6)
  • Blackwell Publishing Ltd
  • 1985-1989  (3)
  • 1980-1984  (3)
  • 1975-1979
  • 1955-1959
Document type
Keywords
Publisher
  • Springer  (6)
  • Blackwell Publishing Ltd
Years
  • 1985-1989  (3)
  • 1980-1984  (3)
  • 1975-1979
  • 1955-1959
Year
  • 1
    Electronic Resource
    Electronic Resource
    The principle of “conservation of total axonal arborizations”: massive compensatory sprouting in the hamster subcortical visual system after early tectal lesions (1988)
    Springer
    Experimental brain research 73 (1988), S. 505-518 
    Details
    ISSN: 1432-1106
    Keywords: Visual system ; Neuroplasticity ; Axon-sprouting ; Pruning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Unilateral lesions of the right superior colliculus (SC) were made in hamsters on the day after birth. In order to quantify the extent of abnormal innervation by left eye fibers in the diencephalon and midbrain, the left eye was removed on postnatal day 12 or 36, and after an appropriate survival time, the brains were stained for degenerating axons and axon terminals with the Fink-Heimer method. In additional cases, anterograde transport of 3H proline-leucine or horseradish peroxidase was used to assess left eye connectivity. In agreement with previous reports we found abnormal projections in the ventral nucleus of the lateral geniculate body (LGv), in the lateral posterior nucleus (LP) of the thalamus, and in the left SC (the ‘recrossing’ pathway). We also noted areas of abnormally heavy terminal fields arranged in patches in coronal sections in the dorsal nucleus of the lateral geniculate body (LGd). These patches arise from columns of dense innervation that are oriented along a rostral-to-caudal axis. If the right SC lesion was made large enough to diminish the recrossing pathway, retinofugal axons establish a significantly smaller distal terminal field in the left SC. In these cases, a corresponding increase in the size of terminal fields in all major proximal structures (LGd, LGv, LP, DTN) was observed. The sum of abnormal proximal growth (“compensatory sprouting”) was found to truly compensate for the distal loss of terminals. The evaluation of hamsters in which left eye connectivity was assessed at the age of 12 days revealed that lesion-induced patches of abnormal growth have already reached their full size by that time. These findings provide evidence for the ‘pruning -effect’ and demonstrate that retinofugal axons support a fixed number of terminal arborizations (the principle of ‘conservation of total axonal arborizations’).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406608
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Behavior evoked by electrical stimulation of the hamster superior colliculus (1988)
    Springer
    Experimental brain research 73 (1988), S. 595-605 
    Details
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Brain stimulation ; Orienting behavior ; Defensive behavior ; Hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Syrian golden hamsters were implanted with fixed or moveable stimulating electrodes aimed at the superior colliculus (SC). Behavior was observed in response to trains of 0.1 ms pulses at 200 Hz while the animals were moving freely in an open arena or in their home cages. At threshold stimulating currents, the responses consisted almost entirely of freezing or contraversive turning, which occurred in two forms: fast turns, resembling orienting movements to sunflower seeds, and slow turns that were smooth and continuous. Other responses, including head raising and lowering, ipsiversive turning and backing movements were seen occasionally. Increasing the stimulating current usually gave a variety of responses, including circling movements, prolonged freezing, ipsilateral movements and running escape behavior. The sites in SC giving freezes at threshold tended to be located superficially (SO and above), or deep (SGP and below), while sites giving turns were in the intermediate layers. Most freeze sites occurred in the rostro-medial SC that represents the upper visual field, while turn sites occurred predominantly in caudo-lateral SC. Apart from the turns, most of the stimulated responses resembled natural defensive behavior, supporting the view that SC in rodents plays a role in organizing responses to predators, as well as in orienting behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406619
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  • 3
    Electronic Resource
    Electronic Resource
    Compressed retinotectal projection in hamsters: Fewer ganglion cells project to tectum after neonatal tectal lesions (1981)
    Springer
    Experimental brain research 43 (1981), S. 261-269 
    Details
    ISSN: 1432-1106
    Keywords: Hamster ; Superior colliculus ; Compression ; Ganglion cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After partial ablation of the superior colliculus (tectum) in neonatal hamsters, the whole extent of the visual field comes to be represented in a compressed map on the remaining tectal fragment. However, the total volume of tectal tissue in which retinotectal fibers arborize is less than normal. These observations suggest that the retinal ganglion cells which arborize in this reduced volume might arise throughout the whole extent of the retina but be fewer in number than normal. Alternatively, the ganglion cells which project to the tectum might be normal in number but reduced in terminal arbor size. To distinguish between these possibilities, we have used tectal injections of horseradish peroxidase to label retinal ganglion cells which project to the tectum. The numbers of labelled cells per mm2 of retina were counted in selected regions. In hamsters with small lesions, which left 80–85% of the tectum intact, the density of labelled retinal ganglion cells was normal. However, in hamsters with larger lesions, the density of labelled cells was significantly lower than normal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238367
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  • 4
    Electronic Resource
    Electronic Resource
    Voltage sensitive, high-conductance chloride channels in the luminal membrane of cultured pulmonary alveolar (type II) cells (1985)
    Springer
    Pflügers Archiv 404 (1985), S. 354-357 
    Details
    ISSN: 1432-2013
    Keywords: Patch-clamp ; Chloride channels ; Pulmonary epithelium ; Cultured epithelial cells ; Cystic fibrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The properties of ion channels in patches from the luminal membrane of cultured monolayers of type II alveolar epithelial cells from adult rat lung have been studied. In excised patches, prepared as described to yield the “outside-out” configuration (with cesium ions in the bathing solutions to suppress currents arising from potassium channels), we observed anion-selective channels with a conductance of 350–400 pS, and burst lengths lasting seconds. When patches were bathed in solutions with equal chloride concentrations, channels opened and closed spontaneously at membrane voltages close to zero, but tended to close when the potential was shifted by ±10 mV, particularly in the negative direction. Other anions could pass through these channels with a permeability sequence of I(1.5)〉Br(1.02)=〉Cl(1.00)〉NO3(0.9)〉gluconate(0.6) but there was a very low permeability for sodium (P Na/P Cl=0.015±0.006). Calcium ions reduced channel conductance. The channels probably have a role to play in salt absorption by this epithelium, but insufficient information is available about how sodium crosses it for the role of the anion channels in transport to be defined with confidence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585348
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  • 5
    Electronic Resource
    Electronic Resource
    Morphometric and chronobiological studies on the dynamics of the nuclear envelope and the nucleolus during mitosis of the colorless phytoflagellatePolytoma papillatum (1983)
    Springer
    Protoplasma 118 (1983), S. 19-35 
    Details
    ISSN: 1615-6102
    Keywords: Morphometry ; Mitosis ; Nuclear envelope ; Nucleolus ; Polytoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Quantitative electron microscopy of serial sections was used to study the cyclical changes in the nucleus ofPolytoma papillatum during its vegetative life cycle with special reference to mitosis. Particular attention was paid to the fluctuations in the nuclear volume, the nuclear envelope, and the nucleolus. Whereas a volumetric balance exists between the cell (100%) and the nucleus (ca. 8%) from early interphase to late anaphase, the nucleus-to-cell volume ratio is gradually reduced up to ca. 2% during telophase. This disproportion is gradually equalized during cytokinesis. The decrease in nuclear size is brought about by: (a) Constrictive abscission of hernia-like protrusions of the nucleus (“blebbing process”); (b) Ade novo production of membraneous septa across peripheral regions of the nucleus (“internal septation”). Just before or immediately after completion of this internal compartmentalization of the nucleus, the original envelope opens, releasing a portion of nucleoplasm into the cytoplasm (“membrane sluice process”); (c) Gaps in the nuclear envelope were occasionally found during telophase and may also permit nucleoplasm to leak out. Disorganization of the nucleolos, which is preceded by blending of its two major components (pars fibrosa, pars granulosa) starts at prophase via fragmentation. Subsequent dispersion continues until the nucleolus is more or less homogeneously distributed across the metaphase nucleus. During anaphase a good deal of the preexisting material recondenses around the separating chromosomes, but a considerable amount remains dispersed in the nucleoplasm and is extruded into the cytoplasm during nuclear volume reduction. Reorganization of the nucleolus occurs during telophase and early cytokinesis via further coalescence of the recondensed material and simultaneous reconstruction of the spatial separation of pars fibrosa and pars granulosa. Morphofunctional aspects of nucleo- and nucleologenesis are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01284743
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  • 6
    Electronic Resource
    Electronic Resource
    Morphometric analysis of several intracellular events occurring during the vegetative life cycle of the unicellular algaPolytoma papillatum (1982)
    Springer
    Protoplasma 110 (1982), S. 185-195 
    Details
    ISSN: 1615-6102
    Keywords: Morphometry ; Life cycle ; Chondriome ; Nucleus ; Leucoplast ; Polytoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Quantitative electron microscopy of serial sections was used to study thePolytoma papillatum cell and some of its constituents (nucleus, chondriome, leucoplast) during its vegetative life cycle. The volumes of cells just entering into or passing through mitosis varied considerably and seemed to determine the number of subsequent division processes. Whereas a volumetric balance existed between the cell (100%) and the chondriome (8–9%) during the whole life cycle, there was a correlation between cell and nuclear volumes (8–10%) only during interphase growth and the onset of mitosis. At telophase the nucleus-to-cell-volume ratio was reduced to 2%, but gradually increased during cytokinesis (4.6% at early cytokinesis; 6.5% at late cytokinesis) until it reached the initial value again in newly formed daughter cells. The leucoplast-to-cell-volume ratio (10–26%) varied considerably without any recognizable dependence upon cell cycling. The mean short axis of mitochondrial profiles was proportional to the mean diameter (=thickness) of the mitochondria; the specific surface (outer membrane area per 100 μm3 mitochondrial volume), and the surface-to-volume ratio changed rhythmically. Changes in mitochondrial surface-to-volume ratio (Sc/Vc) were apparently correlated with changes in mitochondrial diameter (Dc). This relationship can be approximately described by the function Sc/Vc=4/Dc. Deviations of the surface-to-volume ratios of the nuclei from the surface-to-volume ratios of idealized spheres of equal size, indicating profound changes in nuclear shape, were found mainly during mitosis. Results were compared with those obtained from other morphometric investigations and discussed with regard to their functional meaning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283321
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