title: Effect of oocyte-secreted factors on porcine in vitro maturation, cumulus expansion and developmental competence of parthenotes.
abstract: The oocyte is known from recent studies in the mouse, cow, sheep and human to be a central regulator of follicular cell function. However, in the pig, little information is known about the regulation of cumulus expansion by oocyte-secreted factors and oocyte quality. We investigated the possible effects of oocyte-secreted factors during in vitro maturation on cumulus expansion and on porcine oocytes as judged by subsequent embryonic development after parthenogenetic activation. Cumulus-oocyte complexes (COC) from antral follicles of pig ovaries collected from a local abattoir were divided into control and treatment groups and were cultured in tissue culture medium 199 supplemented with follicle-stimulating hormone. Treatment groups consisted of increasing numbers of denuded oocytes (DO) co-cultured with COC (at ratios of COC to DO of 1:1, 1:2, 1:3, 1:4 and 1:5). After incubation for 44 h, cumulus expansion and maturation rates were assessed and oocytes were activated parthenogenetically. Cumulus expansion in the 1 COC:4 DO and 1 COC:5 DO groups was low and altered because full dispersion of the outer layer did not occur. Cell viability was not affected, as measured by the automated cell counter, but scanning electron microscopy revealed only a scanty extracellular matrix. Blastocyst rate was significantly higher in the 1 COC:4 DO (34.4%) and in the 1 COC:5 DO (34.9%) groups (p < 0.05) when compared with other groups. Maturation rate, cleavage rate and total cell number showed no significant difference between control and treatment groups. Amplification by reverse transcription polymerase chain reaction (RT-PCR) showed up-regulation of growth differentiation factor 9 (GDF9) in the cumulus cells in the 1 COC:4 DO group at 44 h. We conclude that denuded porcine oocytes could improve the maturation of COC as evidenced by increased blastocyst development in the 1 COC:4 DO, even though cumulus expansion was poor. This improvement could be a result of the GDF9 up-regulation.
authors.affiliation: Department of Theriogenology and Biotechnology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Korea.
authors.forename: Ma Ninia L
authors.initials: MN
authors.lastname: Gomez
authors.forename: Jung Taek
authors.initials: JT
authors.lastname: Kang
authors.forename: Ok Jae
authors.initials: OJ
authors.lastname: Koo
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Dae Kee
authors.initials: DK
authors.lastname: Kwon
authors.forename: Sol Ji
authors.initials: SJ
authors.lastname: Park
authors.forename: Mohammad
authors.initials: M
authors.lastname: Atikuzzaman
authors.forename: So Gun
authors.initials: SG
authors.lastname: Hong
authors.forename: Goo
authors.initials: G
authors.lastname: Jang
authors.forename: Byeong Chun
authors.initials: BC
authors.lastname: Lee
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects / Q000502:physiology*; D055430:Bone Morphogenetic Protein 15 / Q000235:genetics; D002470:Cell Survival; D003470:Culture Media / Q000494:pharmacology; D054885:Cumulus Cells / Q000187:drug effects*; D047108:Embryonic Development; D005260:Female; D018507:Gene Expression Regulation, Developmental; D055429:Growth Differentiation Factor 9 / Q000235:genetics; D008855:Microscopy, Electron, Scanning; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010312:Parthenogenesis; D034421:Sus scrofa; D015854:Up-Regulation
chemical_list: D055430:Bone Morphogenetic Protein 15; D003470:Culture Media; D055429:Growth Differentiation Factor 9