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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 44 (1988), S. 910-919 
    ISSN: 1420-9071
    Keywords: Heart embryology ; developmental biology ; differentiation ; morphogenesis ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The subject of heart development has attracted the interest of many embryologists over the last two centuries. As a result, the main morphologic features of the developmental anatomy of the heart are already well established. Although there are still some controversial points, and there is probably much descriptive work yet to be done, emphasis is currently being placed on developmental mechanisms rather than simply on descriptive facts. The availability of new techniques and the overall advances in biological research are placing heart embryology in a new perspective. Today, we do not simply ask whether one or another embryonic structure arises further right or further left; instead, we are studying how cells, tissues, and their microenvironment interrelate at the several levels of biological organization (from the gene upwards) so as to give rise to a mature organ with a distinct shape and well-established functions. This paper attempts to review some of the basic aspects of the developmental anatomy of the heart. Descriptive embryology is used here as a tool. Emphasis is placed on developmental mechanisms, and on the present knowledge of how these mechanisms are related to the structural development of the heart.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 163 (1981), S. 77-85 
    ISSN: 1432-0568
    Keywords: Golgi apparatus ; Interkinetic nuclear migration ; Cell polarity ; Developing lens ; Developing neural retina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A quantitative evaluation of the positional changes of the Golgi apparatus during the invagination of the lens placode and the presumptive neural retina of the chick embryo was carried out by silver impregnation. The Golgi apparatus is predominantly polarized in the apical process of the elongated interphasic cells; however, basal and lateral positions are also present. When the nuclei are located close to the luminal surface, basal and lateral positions increase significantly showing that a loss of Golgi apparatus polarization takes place, associated with the mitotic cycle. At the beginning of the invagination of lens and neural retina rudiments, a marked shift in orientation occurs between lateral and apical positions of the Golgi apparatus; this is associated with the nuclei located close to the luminal surface. The possible significance of these results is related to some processes concerning the invagination of these rudiments, such as interkinetic nuclear migration and secretion of extracellular materials.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0568
    Keywords: Heart ; Endocardial cushions ; Cell migration ; Fibronectin ; Fibronectin peptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During heart development in the chick some of the endocardial cells that cover the cushion areas leave the cushion endocardium, seed the underlying cardiac jelly, and are transformed into mesenchyme. Cushion mesenchymal (CM) cells migrate from the endocardium toward the myocardium using the cardiac jelly as substratum. Developing cushions have been microinjected with fibronectin (FN), antifibronectin antibodies (AbFN), and four synthetic peptide probes. Two of these peptides (P7 and P10) contained the sequence Arg-GlyAsp-Ser (RGDS), while the other two (P15 and PColl) did not. Cushion area, individual cell area, cell density, cell orientation and a factor of form were evaluated in both experimental and control cushions. CM cell migration was inhibited by FN and AbFN, only partially inhibited by P10 and unaffected by P7. Cushions injected with P15 and PColl were unaffected. These results can be explained by steric modifications of the extracellular matrix, that may render cardiac jelly nonpermissive for CM cell migration, or by interaction of the substances injected at the endocardial cell surface. Migrating CM cells do not present any preferential orientation in any particular direction. CM cell migration seems to depend upon intrinsic migratory behaviour and the presence of FN at the CM cell surface. The enforcement of the direction of CM cell migration does not appear to rely upon matrix signals but be the result of randomly migrating cells becoming distributed more evenly in the matrix.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 57 (2000), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The bulbus arteriosus, ‘windkessel’, of several species of stenothermal and temperate teleosts has been studied by conventional light microscopy and electron microscopy. The bulbus wall is divided into an endocardium, ridges, and middle and external layers. The endocardium of all species shows moderately-dense bodies, which vary widely although the significance is not known. The endocardium in Antarctic teleosts invaginates into the ridge tissue to form solid epithelial cords that show signs of active secretion related to protective substances. Cords also form in serranidic and sparidic species, but signs of active secretion are not evident. The ridges consist of cells within a filamentous meshwork. Ridge cells appear to be smooth muscle cells that undergo a phenotypic transition from the endocardium toward the middle layer. Middle layer cells are typical smooth muscle cells surrounded by a filamentous matrix. The appearance and composition of the extracellular matrix varies widely among species, with those from the Antarctic lacking collagen and elastin fibres. The external layer is a collagenous matrix that contains fibroblasts, blood vessels and nerves. In most Antarctic teleost species this layer lacks blood vessels, but contains nerve fibres. Some of these fibres could have a sensory function to control bulbus dilatation. The external layer of Trematomus bernacchii has the appearance of a germinal centre and may be involved in the immune humoral response. The epicardium is atight epithelium that may control passage of substances with the pericardial cavity.
    Type of Medium: Electronic Resource
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