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  • 1
    Electronic Resource
    Electronic Resource
    The Decrease of Pineal Melatonin Production with Age (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 719 (1994), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1994.tb56819.x
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  • 2
    Electronic Resource
    Electronic Resource
    Electron probe X-ray microanalysis of the elemental composition of the pineal gland of young adults and aged rats (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 20 (1996), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Fractures of deep-frozen and freeze-dried pineal glands were analysed for elemental composition by means of X-ray microanalysis with a scanning electron microscope. The results from young adults (3 months old) were compared with those from aged animals (24 months old); significant increases in S, Ca, Al, Si, and Fe were observed in aged animals when compared to young adults. There were no significant differences with Na, Mg, CI, K, Ti, Cr, Mn, Ni, Cu, Zn, whereas a decrease of P was observed in aged animals when compared to young adults. Whether the changes observed in elemental composition have a direct effect on the activity and production of metalloenzymes and the overall physiology of the pineal gland are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1996.tb00237.x
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  • 3
    Electronic Resource
    Electronic Resource
    The pineal gland of the aging rat: Calcium localization and variation in the number of pinealocytes (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 18 (1995), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In the present study, we investigated the population of pinealocytes in the pineal gland of aging rats. Dark and light pinealocytes were analyzed as to their calcium content. Calcium localization was realized in dark and light cells by means of cytochemistry and X-ray microanalysis. Calcium was mainly localized in dark pinealocytes characterized by many ultrastructural signs of degeneration. The number of pinealocytes per square surface of aged rats (28 months) was com-pared to young ones (3–4 months). While there is a significant increase in the number of dark pinealocytes there is a decrease in the total number of pinealo-cytes in aged rats. This age-related loss of pinealocytes may explain the age-related functional decline of the pineal gland activity (e.g., the decrease of the nocturnal melatonin production).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1995.tb00137.x
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  • 4
    Electronic Resource
    Electronic Resource
    Permeability of the pineal gland of the rat to lanthanum: Significance of dark pinealocytes (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 12 (1992), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The permeability of the pineal gland to lanthanum was investigated by means of transmission electron microscopy and X-ray microanalysis. Different pineal cell populations were studied. Light pinealocytes as well as glial cells were not permeated by the tracer lanthanum, which normally stays extracellularly. Dark pinealocytes showing different degrees of degenerative changes are permeated by lanthanum. The loss of plasma membrane integrity explains the entry of lanthanum into these cells. We conclude: (1) the lanthanum tracer can be used as an indicator of an alteration in membrane permeability, (2) dark pinealocytes appear as cells in the state of degeneration and represent a different physiological state than light pinealocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1992.tb00031.x
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  • 5
    Electronic Resource
    Electronic Resource
    Localisation, structure et genèse des concrétions minérales dans le mésentéron des Collemboles Tomoceridae (Insecta, Collembola) (1974)
    Springer
    Zoomorphology 78 (1974), S. 93-109 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le mésentéron des Collemboles est riche en inclusions minérales appelées sphérites. L'étude de leur genèse nous montre qu'ils se forment dans les citernes du réticulum endoplasmique. Leur croissance et leur évolution se poursuivent dans les mêmes citernes par apport de matériel divers. Les sphérites sont formés de nucléi opaques aux électrons entourés de couches concentriques alternativement claires et sombres. Les critaux ≪ âgés ≫ sont souvent associés à des enroulements membranaires. Le rôle physiologique est discuté. Ces concrétions apparaissant dès l'éclosion, peuvent s'éliminer de differentes manières: par extrusion apocrine, par dégénérescence cellulaire et surtout par le renouvellement périodique de l'épithélium intestinal qui se fait à chaque mue. Ces sphérites peuvent représenter une voie d'excrétion par accumulation et semblent jouer le rôle des tubes de Malpighi qui font défaut chez les Collemboles.
    Notes: Summary The mesenteron of Collembola is rich in mineral inclusions called spherites. The study of their genesis shows us that they are produced in the cisternae of the endoplasmic reticulum. Their growing and evolution occur in the same cisternae by adduction of diverse material. The spherites are composed of dark nuclei surrounded by alternatively clear and dark concentric strata. The “aged” cristals are often connected with membraneous windings. The physiological role is discussed. These concretions which appear already after hatching, cancel out by apocrine extrusion, by cellular degeneration and especially by periodic renovation of the intestinal epithelium which occurs at each moulting. These spherites could reflect a process of excretion by accumulation and seem to have the same part as the Malpighian tubules which lack in Collembola.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298468
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  • 6
    Electronic Resource
    Electronic Resource
    Calcium concretions in the pineal gland of aged rats: an ultrastructural and microanalytical study of their biogenesis (1995)
    Springer
    Cell & tissue research 279 (1995), S. 565-573 
    Details
    ISSN: 1432-0878
    Keywords: Pineal gland ; Aging ; X-ray microanalysis ; Calcium concretions ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The genesis of calcium concretions in aged rats was studied by means of transmission and scanning electron microscopy. The potassium pyroantimonate method, combined with X-ray microanalysis, allowed us to study the distribution of cations and calcium. Notable accumulations of calcium (associated with phosphorus) were localized in vesicles, vacuoles, lipid droplets, lipopigments, and mitochondria of dark pinealocytes. The results obtained in the present investigation suggest that these organelles are involved in the genesis of the concretions. The presence of sulfur indicates the existence of an organic matrix. We propose that genesis takes place in dark pinealocytes, which contain more calcium than light pinealocytes. Mineralization foci are some-times associated with cellular debris and enlarge by further apposition of material. Two types of concretions, as determined by electron microscopy and confirmed by electron diffraction, could be observed: the “amorphous” type with concentric layers and the crystalline type with needle-shaped crystals. Once formed, the concretions reach the extracellular space and the cell breaks down. Possible extracellular calcification is suggested in the extracellular calcium-rich floculent material. The mineralization process is interpreted as being an age-related phenomenon and mainly a consequence of the degeneration of pinealocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318168
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  • 7
    Electronic Resource
    Electronic Resource
    Calcium content and concretions of pineal glands of young and old rats (1991)
    Springer
    Cell & tissue research 263 (1991), S. 593-596 
    Details
    ISSN: 1432-0878
    Keywords: Pineal gland ; Concretions ; Calcium ; X-ray microanalysis ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Calcium content and pineal concretions were studied in young (2–3 months) and old (28 months) Wistar rats. Samples, deep-frozen by liquid propane/isopentane and freeze-dried were analysed by means of X-ray microanalysis in a scanning electron microscope. Total semi-quantitative measurements revealed that pineals of old rats showed a marked increase of calcium compared with the pineals of young rats. It is thus suggested that a calcium-rich environment is responsible for the growth of pineal concretions, which only appear in old rats. Pineal calcifications in rats could thus be an indicator of aging and/or of a degenerating state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327294
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  • 8
    Electronic Resource
    Electronic Resource
    Structure and osmoregulatory functions of the intestinal folds in the seawater eel,Anguilla anguilla (1988)
    Springer
    Journal of comparative physiology 158 (1988), S. 45-55 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The epithelium of the anterior intestine in the seawater eel shows very high and narrow folds whose composition and possible role in osmotic regulation were studied. 2. The enterocytes present a basal labyrinth: numerous mitochondria more or less surrounded by infoldings of the basal membrane. In the intestinal folds, the serosal tissue contains lymphocytes, fibrocytes, enterochromaffin cells, capillaries, smooth muscle fibers and collagen fibers. The tissue is less dense at the tip than at the base of the folds. 3. X-ray microanalyses and electrophysiological studies showed that the serosal, spaces are diffusive compartments sustaining ionic gradients. Na+ and Cl− activity decreased and K+ activity increased from the base to the tip of the intestinal folds. 4. Na+ or Cl− gradients are abolished when the co-ion is removed from the bathing solutions. Serosal ouabain has no reproducible effects on the ion gradients, making it impossible to determine whether these gradients result from the activity of the Na+−K+ pump. K+ gradients decreased with serosal barium and increase with mucosal barium. 5. The ion distribution in the serosal compartments together with ultrastructural characteristics are discussed. It is suggested that water absorption occurs involving a basal ion recycling mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692728
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  • 9
    Electronic Resource
    Electronic Resource
    Calcium concretions in the pineal gland of aged rats: an ultrastructural and microanalytical study of their biogenesis (1995)
    Springer
    Cell & tissue research 279 (1995), S. 565-573 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Pineal gland ; Aging ; X-ray microanalysis ; Calcium concretions ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The genesis of calcium concretions in aged rats was studied by means of transmission and scanning electron microscopy. The potassium pyroantimonate method, combined with X-ray microanalysis, allowed us to study the distribution of cations and calcium. Notable accumulations of calcium (associated with phosphorus) were localized in vesicles, vacuoles, lipid droplets, lipopigments, and mitochondria of dark pinealocytes. The results obtained in the present investigation suggest that these organelles are involved in the genesis of the concretions. The presence of sulfur indicates the existence of an organic matrix. We propose that genesis takes place in dark pinealocytes, which contain more calcium than light pinealocytes. Mineralization foci are sometimes associated with cellular debris and enlarge by further apposition of material. Two types of concretions, as determined by electron microscopy and confirmed by electron diffraction, could be observed: the “amorphous” type with concentric layers and the crystalline type with needle-shaped crystals. Once formed, the concretions reach the extracellular space and the cell breaks down. Possible extracellular calcification is suggested in the extracellular calcium-rich floculent material. The mineralization process is interpreted as being an age-related phenomenon and mainly a consequence of the degeneration of pinealocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050315
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    A possible role of collagen fibrils in the process of calcification observed in the capsule of the pineal gland in aging rats (1997)
    Springer
    Cell & tissue research 288 (1997), S. 435-439 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Calcification ; Concretions ; Collagen ; Pineal gland ; Aging ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The relationship between collagen fibrils and calcified concretions exclusively appearing in the pineal gland of adult/aging rats has been investigated. Deposits of lanthanum, which replace calcium ions are distributed along collagen fibrils with a repeating period of about 70 nm. Calcium has been detected histochemically between collagen bundles surrounding extracellular concretions by means of the pyroantimonate method and by X-ray microanalysis. It is associated with phosphorus. The data presented here suggest that collagen fibrils are involved in the genesis and growth of extracellular concretions located in the connective tissue surrounding the pineal gland of aging rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050830
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