title: Early germinal vesicle breakdown is a predictor of high preimplantation developmental competent oocytes in mice.
abstract: The preselection of highly developmentally competent oocytes for in vitro maturation (IVM) is crucial for improving assisted reproductive technology. Although several intrinsic markers of oocyte quality are known to be closely related to the onset of nuclear maturation (germinal vesicle break down, GVBD), a direct comparison between GVBD timing and oocyte quality has never been reported. In this study, we established a non-invasive oocyte evaluation method based on GVBD timing for preselecting more developmental competent oocytes in mice. Because the O2 concentration during IVM may affect the nuclear kinetics, all experiments were performed under two distinct O2 concentrations: 20% and 5% O2. First, we determined the time course of changes in nuclear maturation and preimplantation developmental competence of in vitro-matured oocytes to estimate GVBD timing in high developmental competent oocytes. Two-thirds of oocytes that underwent GVBD in early IVM seemed to mainly contribute to the blastocyst yield. To confirm this result, we compared the preimplantation developmental competence of the early and late GVBD oocytes. Cleavage and blastocyst formation rates of early GVBD oocytes (80.2% and 52.7% under 20% O2, respectively, and 67.6% and 47.3% under 5% O2, respectively) were almost double those of late GVBD oocytes (44.8% and 26.0% under 20% O2, respectively, and 40.4% and 17.9% under 5% O2, respectively). With no observable alterations by checking the timing of GVBD in preimplantation developmental competence, oocyte evaluation based on GVBD timing can be used as an efficient and non-invasive preselection method for high developmental competent oocytes.
authors.affiliation: Laboratory of Cell Engineering,Department of Pharmaceutical Sciences,Ritsumeikan University,Nojihigashi 1-1-1,Kusatsu,Shiga 525 8577,Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Higaki
authors.affiliation: Laboratory of Theriogenology,Department of Veterinary Clinical Sciences,Graduate School of Veterinary Medicine,Hokkaido University,Sapporo,Hokkaido 060-0818,Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Kishi
authors.affiliation: Dairy Cattle Group,Konsen Agricultural Experiment Station,Hokkaido Research Organization,Nakashibetsu,Hokkaido 086-1135,Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Koyama
authors.affiliation: Laboratory of Theriogenology,Department of Veterinary Clinical Sciences,Graduate School of Veterinary Medicine,Hokkaido University,Sapporo,Hokkaido 060-0818,Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Nagano
authors.affiliation: Laboratory of Theriogenology,Department of Veterinary Clinical Sciences,Graduate School of Veterinary Medicine,Hokkaido University,Sapporo,Hokkaido 060-0818,Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Katagiri
authors.affiliation: Laboratory of Cell Engineering,Department of Pharmaceutical Sciences,Ritsumeikan University,Kusatsu,Shiga 525-8577,Japan.
authors.forename: Tatsuyuki
authors.initials: T
authors.lastname: Takada
authors.affiliation: Laboratory of Theriogenology,Department of Veterinary Clinical Sciences,Graduate School of Veterinary Medicine,Hokkaido University,Sapporo,Hokkaido 060-0818,Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D002467:Cell Nucleus; D002478:Cells, Cultured; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro; D059471:In Vitro Oocyte Maturation Techniques / Q000379:methods*; D008297:Male; D008813:Mice, Inbred ICR; D009865:Oocytes / Q000166:cytology* / Q000502:physiology*; D010100:Oxygen
chemical_list: D010100:Oxygen
keywords: Developmental competence; Germinal vesicle breakdown; Mouse; Oocyte