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  • Cats  (3)
  • Electron microscopy  (3)
  • Adaptation  (2)
  • 1
    ISSN: 1432-1106
    Keywords: Adaptation ; Vestibular ; Ocular ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Adaptability of the horizontal vestibulo-ocular reflex (HVOR) and the optokinetic response (OKR) was examined in alert albino rabbits during sustained runs lasting 5–12 h under four different stimulus conditions. (1) Sinusoidal rotation of the rabbit in darkness by 5 ° at 1/10 Hz, or (2) sinusoidal movement of a vertical slit light by 2.5 ° or 5 ° at 1/10 Hz around the optical axis of the stationary rabbit, affected the gain of neither the HVOR nor the OKR. (3) Combination of the stimulus as in (1) with the stationary slit light increased the gain of the HVOR gradually. A plateau at about 140% of the initial control was reached in 5 h. (4) Combination of the stimulus as in (1) with the slit light movement by 10 ° in phase with the turntable decreased the HVOR gain gradually, a plateau being obtained at about 70 % of the initial control in 5 h. Changes of the HVOR gain induced in conditions (3) and (4) were not frequency-specific and accompanied by no significant modification of either the gain or phase of the OKR or the linear property of HVOR-OKR interaction. A small but significant change of the HVOR phase was also detected under the condition (3) but not (4).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 282 (1990), S. 402-407 
    ISSN: 1432-069X
    Keywords: Electron microscopy ; Culture ; Hair cells ; Growth ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cultured hair cells from 4-day-old C3H mice were studied by electron microscopy. The hair roots isolated from the skin by collagenase digestion were dispersed into a cell suspension by treatment with a mixture of trypsin and ethylenediaminetetraacetate. The cells were cultured in MCDB-153 (a medium containing seven growth factors) for 1, 3, 6 or 13 days. The number of cultured cells on day 3 was twice that on day 1, and stayed at the same level until day 13. By electron microscopy, some of the cells cultured for 1 day were seen to be undifferentiated and others already showed differentiation into various hair structures. Such differentiated cells disappeared on day 3 and most of the cells cultured for 3 days were undifferentiated. Cells cultured for 6 days were differentiated showing inner root sheath cell, hair cortical cell and medulla cell structures. The characteristics of these cultured cells corresponded well to those of in vivo cells of the hair tissues from the back skin of 7-day-old C3H mice. On day 13 degeneration occurred in the cultured cells. In none of these cultures were mesenchymal cells, such as fibroblasts, found. The present electron microscopic study reveals that immature cells obtained from mouse hair tissues proliferate in vitro and differentiate into several subpopulations corresponding to those of in vivo cell layers of hair tissues. The present culture technique may be useful for studies of hair cell growth and differentiation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 284 (1992), S. 290-296 
    ISSN: 1432-069X
    Keywords: Cepharanthine ; Minoxidil ; Culture ; Hair cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of cepharanthine and minoxidil on proliferation, differentiation and keratinization of cultured cells from the murine hair apparatus were examined electron microscopically. Both cepharanthine and minoxidil stimulated cell proliferation and delayed initiation of differentiation and keratinization of the cultured cells. On day 6, most control cells (87%) cultured in a 0.03 mM calcium medium without cepharanthine and minoxidil were differentiated into several subpopulations corresponding to those of in vivo cell layers of the hair apparatus, while most of the cells cultured with cepharanthine (71%) or minoxidil (70%) were still immature. On day 13, the number of degenerated cells increased (63%) in the control culture, whereas in the culture treated with cepharanthine or minoxidil, cell degeneration scarcely occurred (5% and 8%, respectively). Differentiated cells having tonofilaments were often observed in the cepharanthine- and minoxidil-treated cultures (76% and 72%, respectively). Elevation of extracellular calcium up to 1.0 mM induced keratinization (34%) in the control culture on day 6, while no keratinized cells were observed in the cepharanthine- or minoxidil-treated culture. On day 13 keratinization similarly occurred in the cultures with cepharanthine (30%) or minoxidil (48%). These results show that both cepharanthine and minoxidil may directly influence proliferation, differentiation and keratinization of cultured cells from the hair apparatus.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 281 (1989), S. 254-259 
    ISSN: 1432-069X
    Keywords: Innermost cell layer ; Tonofilaments ; Huxley's cells ; Henle's cells ; Anagen hair follicles ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To elucidate the biologic roles and further cytologic characteristics of the innermost cell (IMC) layer of the outer root sheath (ORS), human anagen hair follicles were ultrastructurally examined. In the lower follicle, the transeversely running tonofilaments in the inner side of the cytoplasm of the IMCs showed a massive accumulation, facing the keratinized part of a Huxley's cell protruding through a Henle's pore. In a rare instance, a spindle-shaped cell was seen between the IMC layer and the keratinized Henle's layer. At the lower isthmus portion, some of the IMCs containing a large number of tonofilaments showed a partial degeneration of the inner side of the cytoplasm. More distally, intercellular spaces between the keratinized IMCs and keratinized Henle's cells were partly dilated and contained amorphous substances. It is suggested that the IMCs in the lower follicle may play a role to support and cover the inner hair structures, tightly as hoops of a barrel. In the isthmus portion, the IMCs may loosely support and guide the keratinized Henle's cells undergoing degeneration.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 6 (1968), S. 247-264 
    ISSN: 1432-1106
    Keywords: Deiters neurones ; Disinhibition ; Cerebellum ; Cats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following the stimulation of cerebellar cortex, a slow depolarization developed in the neurones which were impaled with microelectrodes in the dorsal portion of the nucleus of Deiters. Characteristically, it was produced bilaterally from a wide area of the culmen and, with double shock stimulation at brief intervals, showed a marked potentiation, often in association with a later depression. After repetitive stimulation of the cerebellar cortex the slow depolarization was prolonged for a period of many seconds. Even stimulation of the spinal cord caused similar depolarization. By intracellular injection of currents and ions, the depolarization was shown to be disinhibition, i. e., removal of background inhibition. Accordingly, it was confirmed that there was a steady production of IPSPs in dorsal Deiters neurones, which diminished during the phase of disinhibition. As the possible source of these background IPSPs, the Purkinje cell axons within the nucleus of Deiters were found to be discharging rhythmically at a rate of 20–90/sec, and in fact they were depressed very effectively after cerebellar stimulation. At the same time, volleys along Purkinje cell axons produced by a testing cerebellar stimulation also were diminished, indicating a depression in the excitability of Purkinje cells.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 4 (1968), S. 310-320 
    ISSN: 1432-1106
    Keywords: Deiters neurones ; Cerebellum ; Inhibitory zone ; Cats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary By recording intracellularly from Deiters neurones of cats, there was a survey of those cerebellar areas that, when stimulated, produced inhibitory postsynaptic potentials (IPSPs) monosynaptically in Deiters neurones. The monosynaptic inhibitory area expanded longitudinally mainly along the ipsilateral vermal cortex of the anterior lobe. The ipsilateral cortex of the posterior lobe was also effective in inhibiting Deiters neurones though less prominently than the anterior lobe. The inhibitory fibers could be stimulated in the white matter of the cerebellum, predominantly in the ipsilateral side at rostral regions of nuclei fastigii and interpositus. It was further shown that the monosynaptic inhibition from the anterior and posterior lobes occurs chiefly in the dorsal portion of Deiters nucleus. Since in both the cerebellum and Deiters nucleus the spatial pattern of distribution of the inhibitory fibers conforms to that of the corticovestibular fibers as histologically defined, the experimental findings are in accord with the hypothesis that the cerebellar Purkinje cells are inhibitory in nature.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1106
    Keywords: Axon reflex ; Deiters neurones ; Cerebellar afferents ; Cats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary When recording intracellularly from cat's Deiters neurones, stimulation of the anterior lobe of the cerebellar cortex produced excitatory postsynaptic potentials (EPSPs) monosynaptically, in addition to the inhibitory ones (IPSPs) that were identified previously as being produced via Purkinje cell axons. The EPSPs were induced bilaterally from a wide area of the anterior and posterior lobes of the cerebellum, in contrast to the IPSPs that were evoked only ipsilaterally, mainly from the vermal cortex. The latency of the EPSPs was slightly, but significantly, shorter than that of the IPSPs. The presynaptic impulses responsible for these EPSPs were represented by the discrete field potentials and also by unit spikes of individual fibres. The pathway for these EPSPs and presynaptic impulses was pursued by testing their interference, in the manner of impulse collision and refractoriness, with those induced from various spots within or outside the cerebellum. It is found that the excitatory fibres for Deiters neurones extend transversely, and probably longitudinally too, over the culmen and pass out of the cerebellum through cerebellar peduncles. The major portion of them appears to originate from the medulla and a minority from the spinal cord. It is postulated that cerebellar afferents from these structures have synapses with Deiters neurones via their collateral branches, through which a kind of axon reflex occurs to Deiters neurones during stimulation of the cerebellar cortex.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1614-7456
    Keywords: Quadrupedal locomotion ; Gait pattern ; Adaptation ; Periodic perturbation ; Coupled oscillators ; Limb dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Quadrupeds can acquire new gait patterns with respect to environmental changes. Yanagihara et al. have demonstrated this adaptability by experiments on a decerebrate cat. These experiments indicate that quadrupeds gradually adapt to their environment by repeating locomotion in a steady environment, and that the acquired gait pattern is persistently memorized after the locomotion. Our research aims at formulating a mathematical model of these cats' behavior and constructing a quadrupedal walking robot to realize such adaptive behavior. To date, we have proposed a mathematical description of adaptation at the level of gait pattern generation using neural oscillators. In this paper, we extend it to take into account limb dynamics. We study how to design the interaction of the oscillator and limb dynamics.
    Type of Medium: Electronic Resource
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