title: Coculturing denuded oocytes during the in vitro maturation of bovine cumulus oocyte complexes exerts a synergistic effect on embryo development.
abstract: The present study examined the effect of coculturing cumulus oocyte complexes (COCs) and denuded oocytes (DOs) during in vitro maturation (IVM) on nuclear and cytoplasmic maturation, zona pellucida (ZP) hardening, the pattern of fertilization and glutathione peroxidase 1 (GPX1) gene expression in the oocyte. Furthermore, the rate of embryonic development and the quality of blastocysts were examined for both COCs and DOs. Three IVM conditions were studied: 1) the coculture of 12 COCs and 60 DOs, 2) COC control with 12 COCs, and 3) DO control with 60 DOs. The IVM was performed in a 120-μl droplet of TCM199-based IVM medium. Following IVM, in vitro fertilization (IVF) and in vitro culture (IVC) were conducted separately for the COCs and DOs (DO coculture) from the IVM coculture group. Coculturing COCs and DOs increased the percentage of oocytes reaching the blastocyst stage and the total number of cells per blastocyst in both the COC coculture (44.4 ± 8.6 vs 26.7 ± 9.7%, P < 0.01, and 137.9 ± 24.9 vs 121.7 ± 21.1, P < 0.05) and the DO coculture (20.5 ± 5.0 vs 11.1 ± 2.5%, P < 0.01, and 121.9 ± 27.5 vs 112.3 ± 33.2, P < 0.05) compared to their respective control groups. The synergistic effects of coculturing were detected as increased nuclear and cytoplasmic maturation, the prevention of ZP hardening, increased monospermic fertilization and increased expression of GPX1 in the oocytes in response to endogenous oocyte-secreted factors. In conclusion, coculturing COCs and DOs may be an effective culture system for both intact COCs and immature DOs.
authors.affiliation: Division of Applied Life Science (BK21 Program), Graduate School of Gyeongsang, National University, Republic of Korea.
authors.forename: S R
authors.initials: SR
authors.lastname: Dey
authors.forename: G K
authors.initials: GK
authors.lastname: Deb
authors.forename: A N
authors.initials: AN
authors.lastname: Ha
authors.forename: J I
authors.initials: JI
authors.lastname: Lee
authors.forename: J I
authors.initials: JI
authors.lastname: Bang
authors.forename: K L
authors.initials: KL
authors.lastname: Lee
authors.forename: I K
authors.initials: IK
authors.lastname: Kong
mesh_terms: D000818:Animals; D002417:Cattle / Q000196:embryology*; D018920:Coculture Techniques / Q000662:veterinary; D054885:Cumulus Cells / Q000166:cytology*; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D020869:Gene Expression Profiling; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D059471:In Vitro Oocyte Maturation Techniques / Q000662:veterinary*; D009865:Oocytes / Q000254:growth & development*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D015044:Zona Pellucida / Q000502:physiology; D000094765:Glutathione Peroxidase GPX1; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D010750:Phosphoproteins; D000098682:Steroidogenic Acute Regulatory Protein; D005979:Glutathione Peroxidase; D000094765:Glutathione Peroxidase GPX1