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  • Springer  (5)
  • Nature Publishing Group  (1)
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  • Springer  (5)
  • Nature Publishing Group  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 132 (1970), S. 291-298 
    ISSN: 1432-0568
    Keywords: Egg-cylinder ; Mouse ; Germ layers ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The mouse egg-cylinder prior to and after mesoderm formation was studied by means of electron microscopy. The ultrastructural appearance of the proximal entoderm of both embryonic and extraembryonic segments suggests an intensive absorptive and nutritional activity. Numerous pinocytotic vacuoles, microvilli, primary and secondary lysosomes and fair amounts of rough endoplasmic reticulum and free ribosomes were the most important characteristics of these cells. After mesoderm formation, the extraembryonic entoderm showed the aforementioned characteristics even more prominently, while the cells of embryonic entoderm became flattened and depleted of microvilli and of almost all organelles. The cells of the extraembryonic and embryonic ectoderm prior to and after mesoderm formation had the same ultrastructural appearance as mesodermal cells. The cytoplasm of these cells was replete with free ribosomes, but other organelles such as mitochondria and rough endoplasmic reticulum were few in number. The architecture of all cells of the egg-cylinder except those of the extraembryonic entoderm suggested a very low level of differentiation. The criteria and possibilities for the determination of the degree of differentiation on the ultrastructural level and possible differences in protein synthesis in extraembryonic entoderm as compared with other parts of the embryo are considered.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0568
    Keywords: Cleavage stages ; Egg-cylinder ; Mouse ; Rat ; Hydrolytic enzymes distribution ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The time of appearance and the distribution of alkaline and acid phosphatase and nonspecific esterase was investigated in cleavage and early postimplantation stages of mouse and rat embryos. Alkaline and acid phosphatase appeared for the first time in 8-cell embryos. Activity of both enzymes grew progressively stronger to blastocyst stage. Acid phosphatase activity was revealed in the form of fine and coarse granules distributed evenly in the cytoplasm. Alkaline phosphatase was predominantly localized in plasma membranes. There was no difference in intensity of reaction between trophoblastic cells and the inner cell mass. After implantation acid phosphatase was localized in coarse granules in the apical portion of entodermal cells. With the appearance of mesoderm, the cells of embryonal entoderm became flattened and devoid of acid phosphatase activity which was restricted to cells of extraembryonic entoderm. The activity of nonspecific esterase was not detected in preimplantation stages. In postimplantation embryos it roughly corresponded to the activity of acid phosphatase. Alkaline phosphatase was localized in cell membranes of ectodermal cells. The mesodermal cells of mouse embryo displayed a somewhat weaker activity than ectodermal cells, while in the rat embryo the same layer remained completely nonreactive. Our findings on the distribution of the enzymes mentioned did not reveal any kind of polarity or bilateral symmetry in preimplantation stages. In postimplantation stages acid phosphatase and nonspecific esterase are probably bound to lysosomes and play an important role in embryonic nutrition. The absence of alkaline phosphatase from entodermal cells is somewhat puzzling and suggests that the process of molecular transport in those cells is most probably restricted to endocytosis. Our results suggest that all blastomeres are identical with respect to enzyme distribution and that the first signs of differentiation of enzyme content appear with the formation of germ layers.
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  • 3
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mouse egg-cylinders of C3H/H strain with two and three germ layers were transplanted under the kidney capsule. They developed into well differentiated teratomas and teratocarcinomas. Older embryos developed invariably into teratomas composed of adult tissues only. We consider the period of germ layer inversion as a critical stage when embryonic cells loose their potentiality for uncontrolled growth.
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  • 4
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The organ culture technique was used for the study of early cytodifferentiation in explanted rat and mouse embryonic shields. After 15 daysin vitro the main tissues were differentiated in explants. The full differentiation depended on the presence of homologous serum in the culture medium. 95% oxygen in the atmosphere was either deleterious or without measurable effect if introduced from the beginning or toward the end of the cultivation period, respectively. Some chemically defined media supported the development for only a limited time span during the initial period of cultivation.
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  • 5
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Das Protein-Muster von Gehirn, Herz und Skelettmuskel in spätembryonalen und postnatalen Entwicklungsstadien wurde durch Polyacrylamid-Gel-Elektrophorese untersucht. 2. Adultorgane zeigen Spezifität ihrer Eiweißmuster mit Bezug auf relative Anteile und Verteilung der getrennten Eiweißbanden. 3. Die Eiweiß-Zusammensetzung von morphologisch bereits gut definierten Organen im spätembryonalen Stadium wird nicht verändert durch den Vorgang der Geburt und bleibt erhalten bis in die frühe neonatale Periode. 4. Signifikante Entwicklungsänderungen in der Eiweiß-Zusammensetzung, die zur Bildung des adulten Musters führen, finden zwischen dem 3. und 30. postnatalen Tag statt. 5. Die Ergebnisse und die Limitationen der Methode werden beurteilt mit Bezug auf Anwendbarkeit auf entwicklungsbiologische Studien.
    Notes: Summary 1. Protein composition of rat brain, and of heart and skeletal muscle was analysed by polyacrylamide gel electrophoresis in their late fetal and postnatal development. 2. Adult organs show specificity of their protein patterns as judged from the relative quantitative proportions and distribution of separated protein bands. 3. Protein composition of morphologically already well defined organs in the late fetal stage of development is not changed by the event of birth and is preserved unmodified until the early neonatal period. 4. Significant developmental changes in protein composition leading to formation of adult pattern take place between the 3rd and 30th postnatal day. 5. Results and limitations of the technique applied are evaluated from the point of applicability to developmental studies.
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 227 (1970), S. 503-504 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The egg-cylinder stage at which all extraembryonic material can be dispensed with is the most suitable model to use for elucidating the differentiation and histogenesis of mature tissues. Long term transplantations of rat egg-cylinders have been carried out in our laboratory^(unpublished results of ...
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