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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure of cleavage stages and preimplantation embryos of the baboon (1974)
    Springer
    Anatomy and embryology 147 (1974), S. 45-62 
    Details
    ISSN: 1432-0568
    Keywords: Baboon ; Cleavage stages ; Embryos ; Preimplantation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé La structure et l'ultrastructure des embryons de babouin sont étudiées dans la période précédant l'implantation. Six stades du développement embryonnaire sont observés 2, 3, 4, 5, 7 et 8 jours après la date présumée de fécondation. Dans les 3 premiers cas, on compte respectivement 2, 8 et 24 blastoméres. A 5 jours, il y a 30 à 40 cellules et un nombre dépassant 60, ultérieurement. Des cellules trophoblastiques primitives se différencient à 7 jours et une cavité de segmentation en forme de croissant apparaît au 8 ème jour. La zone pellucide est toujours présente à 8 jours, la période de préimplantation semblant plus longue chez le babouin que chez l'homme. Des particules de type C sont décrites dans la zone pellucide et les espaces périvitellin et interblastomériques. La transformation des mitochondries, des changements dans la répartition des ribosomes, des corps multivésiculaires, pseudocristallins et figures myéliniques, des nucléoles et amas granuleux intra-nucléaires s'observent chez le babouin comme chez certains autres Mammifères; par contre, les faisceaux fibrillaires cytoplasmiques sont absents. L'étude des changements de l'ultrastructure provoqués par des hormones et drogues permettrait de mieux évaluer la nocivité de ces substances pendant les premiers stades du développement embryonnaire des Primates.
    Notes: Summary The baboon preimplantation stages were examined using light and electron microscopy. Six cases were studied at 2, 3, 4, 5, 7 and 8 days estimated fertilization age. The first 3 specimens were composed of 2, 8 and 24 blastomeres respectively. At 5 days, 30 to 40 cells were counted and more than 60 cells in later stages. Primitive “trophoblast cells” differentiate at 7 days and a crescentic blastocoele appears at 8 days. Shedding of the zona pellucida is not observed in the 7 and 8 day specimens. The preimplantation period is longer in the baboon than in man. C-type viruses are observed in the zona pellucida, in the perivitelline and interblastomeric spaces. Microvilli and caveolae cover the periphery of the baboon conceptus. As in many other mammals, transformation of the mitochondria, changes in the ribosomes distribution, multivesicular bodies, myelin figures, nucleoli and intranuclear clusters of granules are described in the baboon. Cytoplasmic fibrous strands are not present as in the mouse. Experiments on the influence of hormones and drugs on ultrastructural changes would help to evaluate the importance of biohazards during the early development of primates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317963
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  • 2
    Electronic Resource
    Electronic Resource
    Measurement of SR Ca2+ content in the presence of caffeine in permeabilised rat cardiac trabeculae (1998)
    Springer
    Pflügers Archiv 437 (1998), S. 139-148 
    Details
    ISSN: 1432-2013
    Keywords: Key words Ca2+ ; Ca2+ -ATPase ; Caffeine ; Cardiac ; Heart ; Ryanodine ; Sarcoplasmic reticulum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This study was designed to measure the Ca2+ content of rat cardiac sarcoplasmic reticulum (SR) after equilibration with normal diastolic levels of Ca2+ (100 nM), in the absence and presence of caffeine. Measurements of [Ca2+] based on Fura-2 fluorescence were made from a limited bath volume (230 nl) containing individual saponin-permeabilised rat cardiac trabeculae. Injection of caffeine (5–40 mM) into this volume caused an initial release of Ca2+ from the SR, but within 30 s the SR was able to re-accumulate a significant proportion of the Ca2+. Ca2+ re-accumulation into the SR could be prevented by removal of ATP to inhibit the SR Ca2+ pump. Incubation of the preparation in an ATP-containing solution containing caffeine (5–40 mM) and 100 nM Ca2+ indicated that the SR’s ability to retain Ca2+ depends inversely on the dose of caffeine. The relative Ca2+ content of the SR after preincubation with caffeine was 86.7±3.5% at a caffeine concentration of 5 mM, 62.5±5.1% at 10 mM caffeine, 37.8±8.1% at 20 mM caffeine and 7.1±1.9% at 40 mM caffeine. Measurement of the SR Ca2+ release in the presence of different BAPTA concentrations was used to calculate (1) the Ca2+-binding capacity of the preparation (equivalent to 245±10 µM BAPTA) and (2) the Ca2+ content of the SR accessed by caffeine after equilibration with 100 nM Ca2+ (186±11 µmol/l cell volume or 5.6 mmol/l SR volume).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050758
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  • 3
    Electronic Resource
    Electronic Resource
    The effects of caffeine and Ca2+ on rigor tension in triton-treated rat ventricular trabeculae (1992)
    Springer
    Pflügers Archiv 421 (1992), S. 343-349 
    Details
    ISSN: 1432-2013
    Keywords: Cardiac muscle ; Rigor tension ; Ca2+ ; Caffeine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ventricular trabeculae from rat heart were chemically skinned with Triton-X100, which disrupts all cellular membranes including the sarcoplasmic reticulum. Trabeculae developed a maintained rigor contracture when adenosine triphosphate was withdrawn from the bathing medium. In all preparations, the final level of rigor force developed in the presence of caffeine (10–40 mM) was greater than under control conditions. However, caffeine failed to increase rigor tension when applied after contracture had fully developed. The effect of caffeine on rigor was maximal at about 15 mM; concentrations greater or less than 15 mM were less effective. On average, caffeine decreased the time required to develop half-maximum rigor force. The caffeine-induced potentiation of rigor force occurred in the effective absence of Ca2+ (10−9 M), in solutions strongly Ca2+-buffered with [ethylenebis(oxonitrilo)]tetraaceticacid (10–50 mM). In all preparations, rigor force was found to be independent of [Ca2+] over the range 10−10 M to about 10−7 M. These results suggest that caffeine affects rigor force by a direct effect on the myofilaments via a mechanism that is independent of Ca2+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374222
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructural and fluorescence histochemical studies on the effects of 6-hydroxydopamine on the rat median eminence (1974)
    Springer
    Cell & tissue research 152 (1974), S. 493-512 
    Details
    ISSN: 1432-0878
    Keywords: Median eminence ; 6-Hydroxydopamine ; Fluorescence ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The extent of degeneration and regeneration of catecholamine-containing nerve fibres in the external layer of the median eminence of the rat has been assessed following treatment with 6-OHDA. Ultrastructural and fluorescence histochemical evidence suggests that nerve terminal degeneration occurs in the external layer of the caudal regions of the median eminence, including the anatomical stem, following intravenous injection of 6-OHDA in a dose of 100 mg/kg. No degeneration in the external layer of the median eminence was observed when the drug was given as sequential intracisternal injections to adult rats or neonatal rats by subcutaneous injections. The fluorescence histochemical studies suggest that regeneration of catecholamine-containing neurons is substantially complete within three weeks of treatment with intravenous 6-OHDA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218934
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  • 5
    Electronic Resource
    Electronic Resource
    The neurosecretory cells of the optic lobe in Carcinus maenas (L) (1975)
    Springer
    Cell & tissue research 156 (1975), S. 403-409 
    Details
    ISSN: 1432-0878
    Keywords: Neurosecretory cells ; Eyestalk ; Carcinus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The six types of neurosecretory cell in the optic lobe of Carcinus maenas described by light microscopy are recognised by electron microscopy. They are categorised according to size, distribution of organelles and type of neurosecretory product. The neuro secretory material, produced as granules by the Golgi bodies, migrates to the cell periphery eventually reaching the sinus gland via the neurosecretory cell axon extension. No change in size occurs in the granules but the density does alter. Each cell type has its own characteristic type of neurosecretory granule based on size and electron density. Multivesicular and lytic bodies in cell types 1, 2, 3,4 and 6 suggest a cycle for degrading neurosecretory material. Such a cycle is not so evident in cell type 5. Peripheral release of neurosecretory material is suggested for cell type 6 although the fate of the material is unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225368
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  • 6
    Electronic Resource
    Electronic Resource
    Ultrastructural features of the developing hypothalamo-hypophysial axis in the rat (1971)
    Springer
    Cell & tissue research 119 (1971), S. 208-226 
    Details
    ISSN: 1432-0878
    Keywords: Median eminence ; Hypophysial portal vessels ; Pars distalis ; Ultrastructure ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Nerve fibres containing granular vesicles first appear in the median eminence of the rat on the 16th foetal day while secretory granules in the cells of the adenohypophysis are not present till the 17th foetal day. These observations suggest that the differentiation and early activity of pars distalis cells may depend on substances elaborated at nerve terminals in the median eminence. Although the loops of the primary plexus of portal vessels do not develop until the 4th postnatal day, substances released by nerve fibres in the neurohypophysis could reach the pars distalis through vessels already present at the 15th foetal day in the mesenchyme between the diencephalon and the adenohypophysis. This view is supported by the fact that the earliest cells to exhibit ultrastructural evidence of secretory activity are in the rostral pole of the pars distalis, the first region of the gland to become vascularized. The earliest granules to appear in the cells of the pars distalis correspond to those which are considered to contain mucoprotein hormones; somatotrophin type granules were seen only in postnatal tissues. The finding that, in the median eminence, the development of granular vesicles precedes that of agranular vesicles is discussed with reference to the times at which neurosecretory materials and monoamines become detectable in the region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00324522
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