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  • Pineal gland  (2)
  • 1985-1989  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Effect of continuous darkness on circadian morphological rhythms in pinealocytes of the Chinese hamster, Cricetulus griseus (1986)
    Springer
    Cell & tissue research 245 (1986), S. 127-134 
    Details
    ISSN: 1432-0878
    Keywords: Pineal gland ; Circadian rhythm ; Nuclear and cytoplasmic volumes ; Synaptic ribbon ; Chromatin ; Cricetulus griseus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Effects of a short-term exposure to continuous darkness on 24-h morphological variations in pinealocytes in the superficial pineal of the Chinese hamster (Cricetulus griseus) were examined. Pinealocytes contained type-1, -2 and -3 synaptic ribbons (SR), which had a central dense structure showing rod-like, various and ring-like profiles, respectively, and the quantity of each type of SR was expressed by SR index. 24-h changes in the type-1 and type-3 SR indices persisted in darkness and thus may be endogenous in nature. As under alternating light and dark (LD) conditions, the type-2 SR indices were almost constant over a 24-h period under continuous darkness, but the indices were larger in animals under darkness than in those under LD conditions. The 24-h variations in the nuclear and cytoplasmic volumes were abolished after exposing animals to darkness for 7 days, suggesting that these rhythms may be regulated exogenously. The amount of condensed chromatin exhibited a circadian change; this rhythm persisted under darkness. The results suggest that 24-h variations in the nuclear and cytoplasmic volumes in pinealocytes of the Chinese hamster are regulated by mechanisms different from those controlling the rhythms in SR and chromatin, and that the changes in the nuclear and cytoplasmic volumes and chromatin are related to the change in synthetic activity of pinealocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218093
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A quantitative study of synaptic ribbons in pinealocytes of adult Chinese hamsters (Cricetulus griseus) under different photoperiodic conditions (1986)
    Springer
    Cell & tissue research 244 (1986), S. 107-113 
    Details
    ISSN: 1432-0878
    Keywords: Pineal gland ; Crcadian rhythm ; Synaptic ribbons ; Photoperiod ; Chinese hamster ; (Cricetulus griseus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synaptic ribbons (SR) in pinealocytes of adult (120–130 day-old) male Chinese hamsters (Cricetulus griseus) were classified into types 1, 2 and 3; these have a central dense structure showing rod-like, various and ringlike profiles, respectively. The central structure of the type-2 SR usually appeared as round, oval or comma-like bodies, and occasionally as plates showing various profiles or clubshaped bodies. The quantity of each type of SR, expressed as the SR index, was determined over a 24-h period under a light/dark regime (LD) 12∶12 or LD 14∶10. On comparing the results obtained from adults with previously published data from young (60–70-days-old) animals under LD 12∶12, it was found that, in both young and adult animals, the type-1 and type-3 SR indices exhibited different 24-h variations, whereas the type-2 SR index remained constant over a 24-h period. In addition, the indices of the type-2 SR, but not those of the other SR types, were found to be significantly larger in adult than in young animals. In adult animals, the effects of the photoperiod were different between the three types of SR. A nocturnal increase in the type-1 SR index was observed under both LD 12∶12 and LD 14∶10, its time course being different for each of these photoperiods. Under LD 14∶10, the type-2 SR index showed a significant 24-h rhythm with larger values during the dark period; this was not observed under LD 12∶12. The type-3 SR index was almost the same under LD 12∶12 and LD 14∶10. The results suggest that pinealocyte SR of the Chinese hamster may be composed of three types of SR, each with a different functional role.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218387
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    Paper (German National Licenses)
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