Spindle Formation and Microtubule Organization During First Division in Reconstructed Rat Embryos Produced by Somatic Cell Nuclear Transfer

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Author(s)

    • SUGAWARA Atsushi
    • Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University
    • INAI Kentaro
    • Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University
    • SASADA Hiroshi
    • Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University
    • SATO Eimei
    • Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University

Abstract

The present study was conducted to demonstrate the spindle formation and behavior of chromosomes and microtubules during first division in reconstructed rat embryos produced by somatic cell nuclear transfer (SCNT) with cumulus cell nuclei. To demonstrate the effect of oocyte aging after ovulation on the cleavage of SCNT embryos, micromanipulation was carried out 11, 15 and 18 h after injection of hCG. SCNT oocytes were activated by incubation in culture medium supplemented with 5 <i>μ</i>M ionomycin for 5 min followed by treatment with 2 mM 6-dimethylaminopurine (6-DMAP) in mR1ECM for 2-3 h. For immunocytochemical observation, the SCNT embryos were incubated with monoclonal anti-α-tubulin antibody and then fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse IgG. Cleavage rates were significantly higher for oocytes collected after 15 and 18 h rather than for those collected 11 h after injection of hCG (56 and 53%, respectively <i>vs.</i> 28%; P<0.05). Premature chromosome condensation occurred before activation of the SCNT oocytes, but adequate spindle formation was only rarely observed. The distribution of microtubules in SCNT embryos after activation was different from those of fertilized and parthenogenic oocytes, i.e., a dense microtubule organization shaped like a ring was observed. Eighteen to 20 h post-activation, most SCNT embryos were in the 2-cell stage, but no nucleoli were clearly visible, which was quite different from the fertilized oocytes. In addition, first division with and without small cellular bodies containing DNA was observed in the rat SCNT embryos in some cases. The present study suggests that reorganization of transferred nuclei in rat SCNT embryos may be inadequate in terms of formation of the mitotic assembly and nucleolar reorganization.<br>

Journal

  • Journal of Reproduction and Development

    Journal of Reproduction and Development 53(4), 835-842, 2007-08-01

    THE SOCIETY FOR REPRODUCTION AND DEVELOPMENT

References:  30

Cited by:  1

Codes

  • NII Article ID (NAID)
    10020003952
  • NII NACSIS-CAT ID (NCID)
    AA10936678
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    09168818
  • NDL Article ID
    8882906
  • NDL Source Classification
    ZR22(科学技術--農林水産--畜産)
  • NDL Call No.
    Z54-H305
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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