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  • Key words Somite  (2)
  • Key words Myogenesis  (1)
  • Key words Nuchal translucency • Human • Mouse • Fetus • Embryo • Trisomy 16 • Trisomy 21 • Trisomy 18 • Trisomy 13 • Gene expression • Collagen type I • Collagen type III • Collagen type IV • Collagen type V • Collagen type VI • Laminin • Fibronectin • Skin • Monoclonal antibodies • Polyclonal antibodies • Immunohistochemistry • In situ hybridization • mRNA • Northern blot • Electron microscopy • Immunogold electron microscopy • Gene dosage effect  (1)
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 202 (2000), S. 195-200 
    ISSN: 1432-0568
    Keywords: Key words Somite ; Resegmentation ; Quail-chick chimera ; Spinal column ; Rib
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  According to the concept of resegmentation, the boundaries of vertebrae are shifted one half a segment compared with somite boundaries. This theory has been experimentally confirmed by interspecific transplantations of single somites. Due to the difficulty of exactly orientating individual somites in the host embryo, the outcome and interpretations of these experiments have occasionally been questioned. This is especially true for the formation of neural arches, their processes, and the ribs. We reinvestigated the formation of vertebrae in the avian embryo by grafting one and one half somites from quail to chick embryos. This method eliminates the possibility of a wrong somite orientation in the host embryo. Results show that the vertebral body, the neural arch and its processes are made up of material of two adjacent somites. This is also true for the rib, with the exception of the costal head, which is formed by only one somite. Whereas in the proximal part of the costal body the chick and quail cell regions border on each other in the middle of the rib, in its distal part quail cells gradually begin to mix with chick cells. The intersegmental muscles and their skeletal attachments sites are formed from the same somite. These results support and complete the data of previous studies and confirm the resegmentation concept.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-0393
    Keywords: Key words Nuchal translucency • Human • Mouse • Fetus • Embryo • Trisomy 16 • Trisomy 21 • Trisomy 18 • Trisomy 13 • Gene expression • Collagen type I • Collagen type III • Collagen type IV • Collagen type V • Collagen type VI • Laminin • Fibronectin • Skin • Monoclonal antibodies • Polyclonal antibodies • Immunohistochemistry • In situ hybridization • mRNA • Northern blot • Electron microscopy • Immunogold electron microscopy • Gene dosage effect ; Schlüsselwörter Nuchal translucency • Trisomie • Genexpression • Kollagen • Immunhistochemie • Ductus venosus • Gendosis Effekt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei etwa 80 % der Feten mit Trisomie 21, 18 oder 13 und dem Turner-Syndrom kann eine Flüssigkeitsansammlung in der Nackenregion zwischen der 10. und 14. SSW beobachtet werden. Diese macht sich als erhöhter Meßwert bei der „nuchal-translucency“ Ultraschalluntersuchung bemerkbar. Die Pathophysiologie dieses allgemein zu beobachtenden Phänotypes unterschiedlicher chromosomaler Störungen ist unklar, aber es gibt einige Hinweise, daß einer der Mechanismen kardiale Herzinsuffizienz sein könnte. Man führt dies auf Anomalien des Herzens und der großen Gefäße zurück, sowie auf Veränderungen der extrazellulären Matrix von Geweben und in der Haut. Letztere könnte Folge eines Gendosiseffekts der 3 Genkopien bei Trisomien, anstatt der normalerweise vorliegenden 2 Genkopien sein, die zu einer Veränderung der extrazellulären Matrix der Haut oder einer abnormalen Entwicklung des Herzens und der großen Arterien führen.
    Notes: Summary In about 80 % of fetuses with trisomies 21, 18 or 13 and Turner syndrome there is an increased collection of fluid in the neck region that can be visualized sonographically at 10–14 weeks gestation as increased nuchal translucency thickness. The pathophysiology of this common phenotypic expression of different chromosomal abnormalities is uncertain, but there is some evidence that the underlying mechanism may be cardiac failure, possibly due to abnormalities of the heart and great arteries, and altered composition of the extracellular matrix of tissues, which can be also noticed in the skin. The latter may be due to a gene dosage effect of the three rather than the normal two copies of genes found in trisomies, causing an alteration of the extracellular matrix in the skin or abnormal development of the heart and great arteries.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 198 (1998), S. 255-265 
    ISSN: 1432-0568
    Keywords: Key words Somite ; Pax-1 ; Twist ; Regeneration ; Chick embryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The question of regeneration after experimental somite extirpation has been controversial in the literature. While all workers agree that repair of the defects occurs, results concerning the extent and mechanism of this process, as well as the origin of the cells filling the defect, show great discrepancies. Our approach towards a re-examination of this question involved microsurgical removal of individual somites in 2-day-chick embryos in combination with grafting of quail somites and lateral plate. We show that the defect in the paraxial mesoderm is filled within a day after extirpation and that the reconstituting cells are derived only from the cranial and caudal somites, but not from the contralateral somites or from the lateral plate. There are no indications of an increase of proliferation in the neighbouring somites. In order to examine the differentiation capacities of the cells that fill the defect, we used immunohistochemistry and in situ-hybridization. We show that the cells in the defect are mesenchymal in morphology and express Pax-1 and Twist. There are a few desmin-positive cells in the defect that can be shown to derive from adjacent somites. An epithelial dermomyotome and myotome are absent at the operation site. Neural crest cells do not participate in the reconstitution of the defect. We conclude that cells in the defect either already have or adopt a ventral somitic (sclerotomal) identity, whereas derivatives with dorsal identity are absent from the defect except for a few individual cells.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 296 (1999), S. 199-212 
    ISSN: 1432-0878
    Keywords: Key words Myogenesis ; Differentiation ; bHLH ; Transcription factors ; MADS-box transcription factors ; pax genes ; Cell migration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The skeletal body muscle of vertebrates is derived from segmentally arranged mesodermal structures, the somites. Only the dorsal epithelial half of the somite, the dermomyotome, gives rise to muscle cells during normal development. Head muscle takes its origin from the somites, the unsegmented paraxial head mesoderm and the prechordal mesoderm. Some muscle precursor cells, for instance those for limb and tongue muscle, migrate over considerable distances before differentiating at their target sites. In recent years, our understanding of the molecular events underlying myogenesis has increased considerably. Muscle differentiation is preceded by several steps during which precursor cells are specified. Markers of myogenic specification are myf5, myoD, mrf4 and myogenin, which encode transcription factors of the basic helix-loop-helix family. These factors bind to promoters of many muscle-specific genes and interact with MEF2 (myocyte enhancer binding factor-2) belonging to the MADS (MCM1, agamous, deficiens, serum response factor) box transcription factors. Signalling events leading to myogenic precursor cell specification and to the formation of muscle fibres are being elucidated. Inductive signals emanate from the neural tube, notochord and ectoderm. Controversial findings concerning the role of the notochord and neural tube in muscle development suggest that the epigenetic events leading to myogenesis are more complex than originally anticipated. Signals from the lateral plate counteract those from the axial organs and induce the locally restricted emigration of muscle precursor cells. Future investigations will have to show how signalling molecules and their receptors interact in the process of fine-tuning muscle formation in the embryo.
    Type of Medium: Electronic Resource
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