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  • 1
    Electronic Resource
    Electronic Resource
    Granule containing cells and fibres in the sinus venosus of elasmobranchs (1975)
    Springer
    Cell & tissue research 163 (1975), S. 471-490 
    Details
    ISSN: 1432-0878
    Keywords: Cardiac ultrastructure (Elasmobranchs) ; Endocrine cells ; Neurons ; Catecholamines ; Histochemistry/Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The concentrations of catecholamines in the heart chambers of elasmobranchs were measured by the fluorimetric method of Bertler et al. (1958). Noradrenaline (NA) can be detected in all the chambers, but the sinus venosus is by far the richest in NA. This can either be due to the presence of storage sites for this amine in the sinus wall, or to a transport of amine to the sinus venosus from the anterior chromaffin bodies. The sinus wall contains large numbers of “granule containing cells” and axon-like processes, both with numerous dense-core vesicles of about 1800 Å diameter. The dense-core vesicles contain a uranophilic matrix indicating the presence of protein, phospholipids and/or nucleic acid. The reactions failed to demonstrate amine, which may be due to a loss of amine by diffusion, to a relatively low intravesicular amine concentration, or, to the absence of amines in these granule-containing cells and processes. Heavy accumulations of granule-containing processes occur in the subendothelial area. The endothelium contains fenestrae and pores through which granule-containing fibres protrude into the venous cavity. Granule-containing cells are innervated by presumed cholinergic nerve endings. It is suggested that the granule-containing cells and fibres belong to a neurosecretory system with a cholinergic input, releasing the contents of the dense-core vesicles into the blood stream at the level of the venous cavity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218493
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of calcium in the pigeon papillary muscle as demonstrated by cytochemical studies and X-ray microanalysis (1974)
    Springer
    Cell & tissue research 155 (1974), S. 57-74 
    Details
    ISSN: 1432-0878
    Keywords: Cardiac ultrastructure ; Sarcoplasmic reticulum ; Myocardial calcium localization ; EDTA/EGTA ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intracellular localization of calcium as an antimonate precipitate is studied in myocardial cells of a non-mammalian vertebrate. Pigeon papillary muscles are pretreated in a calcium-free potassium solution containing 60 mM KSb (OH)6, and fixed in 1 % OsO1 containing the same concentration of antimonate. Calcium is chelated by K-EDTA or K-BGTA, in part separating it from the sodium-calcium antimonate. Atomic absorption spectrophotometry is employed to study the precipitate formation when sodium and calcium ions are added to a pH controlled antimonate solution. The chelating effect of K-EDTA and K-EGTA on the precipitates is studied by the same method. Both sodium and calcium cations are heavily precipitated by the antimonate anion. More calcium ions are precipitated when sodium ions are also present in the solution. K-EDTA and K-EGTA do not redissolve more than about 50% of the calcium antimonate from a sodium-calcium antimonate precipitate. When calcium cations only are added to the antimonate solution, K-EGTA redissolves about 95% of the calcium antimonate precipitate. A direct evidence for the presence of calcium in the tissue precipitates is given by X-ray microanalyses of 2500 Å thick sections. Calcium antimonate is located to the sarcoplasmic reticulum (SR), the myofibrils, the mitochondria and the nuclei. In the SR, calcium antimonate is consistently found in the subsarcolemmal cisternae of the peripheral couplings (Sommer and Johnson, 1969) and in the Z line cisternae (Saetersdal and Myklebust, 1975) or extended junctional SR (Sommer and Johnson, 1970). Along the myofibrils, calcium antimonate is found at the overlap of thick and thin filaments. In sarcomeres with short I bands, a dense antimonate precipitate consisting of large granules is found at the A-I junction. No calcium is found at the Z lines. The calcium antimonate granules along the myofilaments seem to be related to the length of the sarcomeres. The significance of these findings is discussed in relation to functional aspects of the myocardial cell
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220284
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