Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Cortical membrane-trafficking during the meiotic resumption of Xenopus laevis oocytes (1991)
    Springer
    Cell & tissue research 263 (1991), S. 375-383 
    Details
    ISSN: 1432-0878
    Keywords: Meiosis ; Endoplasmic reticulum, specialized ; Cortical granules, ovum ; Xenopus laevis (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes in the organization of membranous structures in the amphibian oocyte cortex were studied during the process of progesterone-induced meiotic resumption. Progesterone treatment of Xenopus laevis oocytes induced short term and longer term changes in the cortical membranes. In the short term, progesterone induced a burst of endocytosis mediated through coated pits and coated vesicles. Immuno-electron-microscopic localization of progesterone suggested that the progesterone receptor, bound to its ligand, is endocytosed during progesterone-induced endocytosis. Also demonstrated was the existence of a cisternal membrane network, referred to as the primordial cortical endoplasmic reticulum, which surrounds portions of the cortical granules in oocytes. The primordial cortical endoplasmic reticulum is more highly developed in the animal hemisphere than the vegetal hemisphere. Over the long term, during the meiotic resumption, more membrane is recruited into this network to form the cortical endoplasmic reticulum observed by others in the metaphase II egg. This evidence demonstrates that the cortex serves as a site for dynamic changes in membrane organization and that the most extensive changes occur in the animal hemisphere. These data support previous observations that the animal hemisphere is better structured for sperm penetration than is the vegetal hemisphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318779
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Intracellular signals trigger ultrastructural events characteristic of meiotic maturation in oocytes of Xenopus laevis (1989)
    Springer
    Cell & tissue research 255 (1989), S. 183-191 
    Details
    ISSN: 1432-0878
    Keywords: Second messengers ; cAMP ; Oocyte ; Meiosis ; Phorbol ester ; Amphibian ; Xenopus laevis (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Oocytes of Xenopus laevis were treated with agents which induce individual intracellular signals normally evoked during the process of meiotic maturation. Ultrastructural analysis of these oocytes allowed identification of specific second messengers that individually trigger single ultrastructural changes characteristic of the meiotic maturation process: Manipulation of intracellular cAMP levels induced changes in cortical granule position. Cytoplasmic alkalinization triggered a disruption of the annulate lamellae, a specialized organelle in the periphery of oocytes. Activation of protein kinase C caused rapid formation of a cortical endoplasmic reticulum and subsequent disruption of cortical granules. Manipulation of transmembrane calcium flux had varied results dependent upon the agent employed. Two of the treatments, Verapamil and zero external calcium, induced a reorganization in the oocyte periphery. The results indicate that these ultrastructural events are under the control of specific intracellular signals known to be elicited during meiotic maturation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229080
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Transformation of the amphibian oocyte into the egg: Structural and biochemical events (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 16 (1990), S. 202-234 
    Details
    ISSN: 0741-0581
    Keywords: Xenopus ; Meiosis ; Ultrastructure ; Intracellular signals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Amphibian oocytes, arrested in prophase I, are stimulated to progress to metaphase II by progesterone. This process is referred to as meiotic maturation and transforms the oocyte, which cannot support the early events of embryogenesis, into the egg, which can. Meiotic maturation entails global reorganization of cell ultrastructure: In the cell cortex, the plasma membrane flattens and the cortical granules undergo redistribution. In the cell periphery, the annulate lamellae disassemble and the mitochondria become dispersed. In the cell interior, the germinal vesicle becomes disassembled and the meiotic spindles form. Marked changes in the cytoskeleton and mRNA distribution also occur throughout the cell. All of these events are temporally correlated with intracellular signalling events: Fluctuations in cAMP levels, changes in pH, phosphorylation and dephosphorylation, and ion flux changes. Evidence suggests that specific intracellular signals are responsible for specific reorganizations of ultrastructure and mRNA distribution.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060160303
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...