Clin Exp Reprod Med.  2017 Mar;44(1):15-21. 10.5653/cerm.2017.44.1.15.

Effects of sperm insemination on the final meiotic maturation of mouse oocytes arrested at metaphase I after in vitro maturation

Affiliations
  • 1Maria Research Center, Seoul, Korea.
  • 2Division of Biotechnology, Korea University, Seoul, Korea. yongko@korea.ac.kr
  • 3Maria Fertility Hospital, Seoul, Korea.

Abstract


OBJECTIVE
The aims of this study were to investigate whether fertilization could induce the resumption of meiosis in mouse oocytes arrested at metaphase I (MI) after in vitro maturation (IVM), and to investigate the effect of Ca²âº chelator treatment at the time of fertilization on the transition from MI to metaphase II (MII).
METHODS
MII-stage and arrested MI-stage mouse oocytes after IVM were fertilized, and then embryonic development was monitored. Blastocysts from each group were transferred into 2.5 days post-coitum pseudo-pregnant ICR mice. MI oocytes after IVM were treated with a Ca²âº chelator to investigate the effect of Ca²âº oscillations on their maturation.
RESULTS
As insemination time increased, the number of oocytes in the MI group that reached the MII stage also increased. The blastocyst rates and total cell numbers in the MII group were significantly higher than in the MI group. No pregnancy occurred in the MI group, but 10 pregnancies were achieved (10 of 12) in the MII group. The proportion of MI oocytes that matured to MII oocytes after fertilization was significantly higher in the non-treated group than in the Ca²âº chelator-treated group.
CONCLUSION
The findings that a higher proportion of MI-arrested oocytes progressed to MII after fertilization and that the MI-to-MII transition was blocked by Ca2+ chelator treatments before fertilization indicate that the maturation of MI oocytes to MII oocytes is associated with intracellular Ca²âº oscillations driven by fertilization.

Keyword

Arrested metaphase I oocyte; Calcium oscillations; Fertilization; In vitro oocyte maturation

MeSH Terms

Animals
Blastocyst
Calcium Signaling
Cell Count
Embryonic Development
Female
Fertilization
In Vitro Oocyte Maturation Techniques
In Vitro Techniques*
Insemination*
Meiosis
Metaphase*
Mice*
Mice, Inbred ICR
Oocytes*
Pregnancy
Spermatozoa*
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