Evaluation of maturation competence of metaphase II oocytes in mice based on the distance between pericentriolar materials of meiotic spindle: Distance of PCM during oocyte maturation

Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University, Sendai, 981-8555, Japan.
Journal of Assisted Reproduction and Genetics (Impact Factor: 1.72). 11/2010; 28(2):157-66. DOI: 10.1007/s10815-010-9496-2
Source: PubMed


To ascertain whether metaphase II (MII) spindle shape influences oocyte competence, we examined the meiotic spindle organization in in vivo ovulated (IVO) oocytes and in spontaneously matured or follicle stimulating hormone (FSH)-induced oocytes.
FSH-induced oocytes matured in Waymouth's MB752/1 or human tubal fluid (HTF) media and oocytes matured spontaneously in the basal medium were obtained, and spindles were detected by immunofluorescence. To evaluate the fertilization-associated differences in spindle morphology, we performed in vitro fertilization and analysed integrin mRNA expression.
The distance between the pericentriolar materials (PCMs) in oocytes matured under all conditions was initially more, but it reduced gradually and increased again thereafter. Therefore, oocytes exhibiting a reduction in the distance between PCMs had the highest development rate to blastocyst in each condition.
These results indicate that the 'maturation competence' of MII oocytes can be evaluated on the basis of the distance between PCMs.

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    ABSTRACT: We investigated the expression of focal adhesion kinase (FAK) in mouse cumulus-oocyte complexes (COCs), as well as the role of FAK phosphorylation at Tyr397 during oocyte maturation. The effect of inhibiting FAK phosphorylation at Tyr397 during in vitro maturation (IVM) on subsequent fertilization and preimplantation embryo development was also examined. Western blotting analyses revealed that total and Tyr397-phosphorylated FAK were expressed in vivo in both cumulus cells and oocytes. Immunocytochemical studies localized this kinase throughout the cytoplasm of cumulus cells and oocytes; in particular, Tyr397-phosphorylated FAK tended to accumulate in regions where cumulus cells contact each other. Interestingly, the in vivo level of Tyr397 phosphorylation in cumulus cells was significantly lower after compared to before cumulus expansion. Addition of FAK inhibitor 14, which specifically blocks phosphorylation at Tyr397, stimulated oocyte meiotic maturation and cumulus expansion during IVM in the absence of follicle-stimulating hormone (FSH). Reverse-transcriptase PCR showed that the mRNA expression of hyaluronan synthase 2 (Has2), a marker of cumulus expansion, was significantly induced in cumulus cells. Subsequent in vitro fertilization and culture showed that more oocytes developed to the blastocyst stage when they were treated with FAK inhibitor 14 during IVM, although the blastocyst total cell number was lower than in oocytes stimulated with FSH. These results indicate that FAK is involved in the maturation of COCs; specifically, phosphorylation at Tyr397 may regulate cumulus expansion via the expression of Has2 mRNA in cumulus cells, which could affect the developmental competence of oocytes. Mol. Reprod. Dev. 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
    Molecular Reproduction and Development 03/2015; 82(3):218-231. DOI:10.1002/mrd.22464 · 2.53 Impact Factor


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