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  • 1
    Electronic Resource
    Electronic Resource
    The fusion of the endocardial cushions in the heart of the chick embryo (1973)
    Springer
    Anatomy and embryology 141 (1973), S. 55-75 
    Details
    ISSN: 1432-0568
    Keywords: Heart ; Endothelial cushion ; Fusion ; Cell interaction ; Electron microscopy ; Chick embryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In an investigation concerning the so-called “fusion” of the atrioventricular endocardial cushions in the heart of the chick embryo the following facts were established: 1. The endocardial cushions in the chick embryo do really fuse. However, the region of fusion is less extensive than is generally accepted. 2. No regressive cellular changes were observed in the fusing endothelia with light or electron microscopy. On the contrary, mitotic activity and possibly even erythroblastic transformation were observed in the endothelium as well as in the subendothelial mesenchyme. 3. Under the light microscope, the process of fusion is characterized by interdigitation of the endothelial cells. In later stages the endothelial character of these cells disappears in such a way as to give rise to one single mesenchymal cushion mass. 4. Under the electron microscope the fusing endothelial cells form extremely long tonguelike cytoplasmic processes which protrude freely into the lumen where they may fuse with similar processes from other endothelial cells of the same side. In this way small compartments become segregated from the lumen. the plasma membrane of the processes may also fuse with the plasma membrane of the cell from which they originate. Alternating persistence and disappearance of the plasma membrane gives rise to many membrane-lined intracellular vesicles. 5. The numerous myelin figures found in and between the endothelial surfaces appear to represent the blind and empty membranous linings stripped off from cytoplasmic processes. The intracellular myelin figures are probably incorporated into the cells in the same way as described above. Apart from this form of endocytosis, signs of conventional micropinocytotic activity are present. 6. The density of endoplasmic reticulum suggests intensified protein synthetic activity, in which membrane-bound as well as free ribosomes and polysomes seem to participate. Moreover, increased mitochondrial density in the cells in the fusion region is evident. 7. Specialized junctional complexes between the plasma membranes in the form of desmosome-like junctions are relatively scarce. 8. Fusion of cytoplasmic tongues of endothelial cells with adjacent endothelial cells of the same side or of the opposite side is responsible for the exchange of large quantities of cytoplasma between endothelial cells and, as a consequence, for displacement of cell boundaries without loss of cell individuality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00523365
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  • 2
    Electronic Resource
    Electronic Resource
    The local expression of adult chicken heart myosins during development (1986)
    Springer
    Anatomy and embryology 174 (1986), S. 187-193 
    Details
    ISSN: 1432-0568
    Keywords: Chicken heart ; Conduction system ; Immunohistochemistry ; Myosin isoforms ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development of the ventricular conducting tissue of the embryonic chicken heart has been studied using a previous finding that morphologically recognizable atrial conducting tissue coexpresses the atrial and the ventricular myosin isoforms. It is found that, by these criteria, at 9 days part of the ventricular conduction system consists of a myocardial ring located around the infundibula of the aorta and truncus pulmonalis. Part of this ring is formed by the retro-aortic root branch. The ring continues via the septal branch into the atrioventricular bundle and its branches, that all express both myosin isoforms. The retroaortic root branch could be traced back as a part of the myocardial wall of the truncus arteriosus at the 4 days embryonic stage. At the 16th day of development, the septal branch, atrioventricular bundle and left and right bundle branches no longer express the atrial isomyosin, but two bundles originating from the septal branch still express both isomyosins, one being the retro-aortic root branch, the other being only immunologically recognizable and directed to the ventral side of the truncus pulmonalis; this latter we call the pulmonary root branch. Both bundles are remnants of the myocardial ring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00824334
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  • 3
    Electronic Resource
    Electronic Resource
    Die Entwicklung des Septum sinus venosi cordis (1960)
    Springer
    Anatomy and embryology 122 (1960), S. 173-196 
    Details
    ISSN: 1432-0568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00521797
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  • 4
    Electronic Resource
    Electronic Resource
    The position of the left and right ventricular outlets during septation (1986)
    Springer
    Anatomy and embryology 175 (1986), S. 147-150 
    Details
    ISSN: 1432-0568
    Keywords: Heart separation ; Aorta ; Pulmonary trunk ; Heart development ; Chicken ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A comparative study was made of the relative position of the outflow tracts of chicken and rat hearts with respect to the ventricles during septation. For this purpose the position of the left and right ventricular outlet including the aortic and pulmonary valve primordia and the left and right ventricle were established with respect to the midsagittal plane of the embryo, using reconstructions of serial sections of chicken (stage 28–30) and rat (stage 28–30) embryos. In the chicken embryo no rotation of the outflow tract occurs, i.e. the position of the aortic and pulmonary valve primordia with respect to the left and right ventricle remains the same. In the rat embryo a clockwise rotation of the aortic and pulmonary valve primordia with respect to the ventricles does occur. This is in fact a detorsion. The left and right ventricle and the left ventricular outlet do not show change in position with regard to the midsagittal plane. The left ventricular outlet always straddles the interventricular septum, both lying in the midsagittal plane. These interspecies differences in the degree of detorsion of the outflow channels before septation may explain the differences in the extent of the region of contact between the endocardial outflow tract ridges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315465
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  • 5
    Electronic Resource
    Electronic Resource
    Isomyosin expression patterns in tubular stages of chicken heart development: a 3-D immunohistochemical analysis (1987)
    Springer
    Anatomy and embryology 177 (1987), S. 81-90 
    Details
    ISSN: 1432-0568
    Keywords: Myosin heavy chain ; Immunohistochemistry ; Heart development ; Conductive tissue ; Pattern formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The 3-D distribution of atrial and ventricular isomyosins is analysed in tubular chicken hearts (stage 12+ to 17 (H/H)) using antibodies specific for adult chicken atrial and ventricular myosin heavy chains, respectively. At stage 12+ (H/H) all myocytes express the atrial isomyosin; furthermore, all myocytes except those originally situated in the dorsolateral wall of the sinu-atrium coexpress the ventricular isomyosin as well. Moreover, it appears that recently incorporated myocardial cells at both ends of the heart tube start with a coexpression of both isomyosins. From stage 14 (H/H) onwards a regional loss of expression of one of either isomyosins is observed in the atrial and ventricular compartment. In this way the single isomyosin expression types that are characteristic for the adult working myocardium of the atria and ventricles arise. So, the isomyosin expression patterns are, unexpectedly, hardly useful to discriminate the different heart parts of the tubular heart. The ventricle, defined by its adult type of isomyosin expression, is even not detectable before stage 14 (H/H). Interestingly, interconnected coexpression areas, which may be precursor conductive tissues, are still present at stage 17 (H/H) in the outflow tract, the ventricular trabeculae, the atrio-ventricular transitional zone and in the sinuatrium. The pattern of isomyosin coexpression was found to correlate with a peristaltoid contraction and a slow conduction velocity, whereas single expression areas correlate with a synchronous contraction and a relatively fast conduction velocity. The possible implications of the changing isomyosin pattern for the differentiation of the tubular myocardium, in particular in relation to the development of the conductive tissues, will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325291
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  • 6
    Electronic Resource
    Electronic Resource
    Toward computerized morphometric facilities: A review of 58 software packages for computer-aided three-dimensional reconstruction, quantification, and picture generation from parallel serial sections (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 216 (1986), S. 449-470 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This review gives an inventory of 58 computer-aided three-dimensional reconstruction applications in the domain of biomedical research. It is devoted to the formulation of a set of recommendations thought to be necessary for improved performance of software packages in this field. These recommendations can be used to select packages and to guide future developments of existing reconstruction systems.The survey is restricted to three-dimensional reconstructions based upon a series of parallel sections of an object. Subjects treated are programming languages, resolution and sampling, input preparation, realignment, local deformation of slices, numerical quantifications, topological complexity, internal representation, display complexity (hidden surfaces, shading, smoothing), structure extraction, descriptive elements, database, data compression, time efficiency of systems and algorithms, hardware configuration, input devices, input media, interactive aids, display devices, and output devices. Information for this survey comes from articles that appeared between 1965 and 1985.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092160402
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  • 7
    Electronic Resource
    Electronic Resource
    Isomyosin expression pattern during formation of the tubular chicken heart: A three-dimensional immunohistochemical analysis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 226 (1990), S. 213-227 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Three-dimensional (3-D) distribution of atrial and ventricular isomyosins is analysed immunohistochemically during the formation of the tubular chicken heart (stage 7 to 12 [H/H]) using antibodies specific for adult chicken atrial and ventricular myosin heavy chains, respectively. This analysis revealed that both types of isomyosins can be first detected at stage 8 (H/H, possessing four pairs of somites), i.e., when the heart primordium still exists as two separate cardiogenic plates. The ventricular type of isomyosin is initially expressed in those areas of cardiogenic plates in the vicinity of the anterior intestinal portal. The atrial type of isomyosin is initially expressed in zones caudal and lateral to the areas of ventricular isomyosin expression. Medial to the atrial isomyosin-expressing areas, cardiogenic plate areas exist that initially lack myosin expression. Those parts of the cardiogenic plates that fuse in front of the anterior intestinal portal, thereby forming the heart tube, are characterized by the expression of both isomyosins; however, the caudolateral parts of the heart primordium maintain their single atrial isomyosin expression during further development. Cardiac contractions are therefore first observed at stage 10 (H/H, possessing ten pairs of somites) in myocardium that coexpresses both isomyosins.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092260211
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