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  • 1
    Digitale Medien
    Digitale Medien
    The pineal gland of the gerbil, Meriones unguiculatus (1979)
    Springer
    Cell & tissue research 204 (1979), S. 111-125 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pinealocytes ; Morphometric analysis ; Superior cervical ganglionectomy ; Fluorescence histochemistry ; Gerbil
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Morphometric analytical procedures were employed to study the pineal gland of the Mongolian gerbil following superior cervical ganglionectomy (SCGX). The purpose of this study was to define the effects of sympathetic denervation on the morphology of the gland at two time periods, 0500 and 1900 h (one hour before lights-on and lights-off, respectively). Fluorescence histochemistry was employed to determine catecholamine and indoleamine content in intact and denervated pineal glands. After SCGX, the pinealocytes decrease in size, concretions are prevented from forming, and the yellow fluorescence in the gland is lost. Following denervation a depression in the volume of most of the pinealocyte organelles, i.e., SER, RER/ribosomes, free cytoplasm, mitochondria and presumptive secretory vesicles, was also observed. However, synaptic ribbons increased in volume in the gerbils that had been killed at 1900 h. It appears that the sympathetic innervation to the pineal gland is a requirement for the presumptive secretory activity of the pinealocytes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235168
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  • 2
    Digitale Medien
    Digitale Medien
    The pineal gland of the gerbil, Meriones unguiculatus (1979)
    Springer
    Cell & tissue research 204 (1979), S. 95-109 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pineal gland ; Gerbil ; Pinealocytes ; Morphometric analysis ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary By means of morphometric analytical procedures, a diurnal rhythm in the cellular volume of gerbil pinealocytes was determined. This rhythm has been attributed primarily to a change in the cytoplasmic volume of the pinealocytes which is low during the daylight hours and increases to reach a peak during the middle of the dark period. At the ultrastructural level, six cytoplasmic components of the pinealocytes were found to exhibit a rhythm: free cytoplasm, smooth endoplasmic reticulum (SER), rough endoplasmic reticulum (RER) and ribosomes, secretory vesicles, microtubules, and mitochondria. The presumptive secretory vesicles and the microtubules reached a peak in volume one hour before lights-off. It is suggested that lights-on and lights-off both signal a decrease in size and/or number of the secretory vesicles. The SER and RER/ribosomes reached their peak volume one hour after lights-off which is interpreted as indicating a peak in indoleamine synthesis and protein synthesis, respectively. The volume of free cytoplasm exhibits two peaks; one occurs one hour before lights-off while the second peak occurs in the middle of the dark phase. It is suggested that, although part of the secretory product of the pinealocyte may be present in dense-cored vesicles, other locations could include the free cytoplasm and clear secretory vesicles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235167
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  • 3
    Digitale Medien
    Digitale Medien
    The pineal gland of the gerbil, Meriones unguiculatus (1978)
    Springer
    Cell & tissue research 193 (1978), S. 323-336 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pineal gland ; Gerbil ; Pinealocytes ; Concretions ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Electron microscopy was employed in a study of the pineal gland of the Mongolian gerbil (Meriones unguiculatus). It was determined that the gerbil pineal gland contains pinealocytes and glial cells with the pinealocytes being the predominant cell type. The pinealocytes contain numerous organelles traditionally considered as being either synthetic or secretory in function such as an extensive Golgi region, smooth (SER) and rough (RER) endoplasmic reticulum, secretory vesicles and microtubules. Other cytoplasmic components are also present in the pinealocytes (synaptic ribbons, subsurface cisternae) for which no function has been assigned. Dense-cored vesicles are rare. Vacuolated pinealocytes are present and appear to be intimately associated with the formation of the pineal concertions. Evidence presented supports the proposal that the concretions form within the vacuoles. Once the concretions reach an enlarged state, the vacuolated pinealocytes break down and the concretions are thus extruded into the extracellular space where they apparently continue to increase in size. The morphology of the glial cells was interpreted as indicative of a high synthetic activity. The glial cells contain predominantly the rough variety of endoplasmic reticulum and form an expansion around the wide perivascular area.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00209044
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  • 4
    Digitale Medien
    Digitale Medien
    Regularly scheduled, day-time, slow-onset 60 Hz electric and magnetic field exposure does not depress serum melatonin concentration in nonhuman primates (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 16 (1995), S. 111-118 
    Details
    ISSN: 0197-8462
    Schlagwort(e): baboon (Papio cynocephalus) ; cannula ; electric field ; magnetic field ; pineal gland ; radioimmunoassay ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Experiments conducted with laboratory rodents indicate that exposure to 60 Hz electric fields or magnetic fields can suppress nocturnal melatonin concentrations in pineal gland and blood. In three experiments employing three field-exposed and three sham-exposed nonhuman primates, each implanted with an indwelling venous cannula to allow repeated blood sampling, we studied the effects of either 6 kV/m and 50 μT (0.5 G) or 30 kV/m and 100 μT (1.0 G) on serum melatonin patterns. The fields were ramped on and off slowly, so that no transients occurred. Extensive quality control for the melatonin assay, computerized control and monitoring of field intensities, and consistent exposure protocols were used. No changes in nocturnal serum melatonin concentration resulted from 6 weeks of day-time exposure with slow field onset/offset and a highly regular exposure protocol. These results indicate that, under the conditions tested, day-time exposure to 60 Hz electric and magnetic fields in combination does not result in melatonin suppression in primates. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bem.2250160711
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  • 5
    Digitale Medien
    Digitale Medien
    Rapid-onset/offset, variably scheduled 60 Hz electric and magnetic field exposure reduces nocturnal serum melatonin concentration in nonhuman primates (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 16 (1995), S. 119-122 
    Details
    ISSN: 0197-8462
    Schlagwort(e): baboon (Papio cynocephalus) ; intermittent ; irregular ; pineal gland ; transient ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Experiments with rodents indicate that power-frequency electric field (EF) or magnetic field (MF) exposure can suppress the normal nocturnal increase in melatonin concentration in pineal gland and blood. In a separate set of three experiments conducted with nonhuman primates, we did not observe melatonin suppression as a result of 6 weeks of day-time exposure to combined 60 Hz electric and magnetic fields (E/MF) with regularly scheduled “slow” E/MF onsets/offsets. The study described here used a different exposure paradigm in which two baboons were exposed to E/MF with “rapid” E/MF onsets/offsets accompanied by EF transients not found with slowly ramped E/MF onset/offset; profound reductions in nocturnal serum melatonin concentration were observed in this experiment. If replicated in a more extensive experiment, the observation of melatonin suppression only in the presence of E/MF transients would suggest that very specific exposure parameters determine the effects of 60 Hz E/MF on melatonin. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bem.2250160712
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