title: OPS vitrification of mouse immature oocytes before or after meiosis: the effect on cumulus cells maintenance and subsequent development.
abstract: Cryopreservation can cause cumulus cell damage around the immature oocytes, which may result in poor subsequent development. To evaluate the effect of the meiosis stage on the cumulus cell cryoinjury and determine the suitable stage for cryopreservation in immature oocytes, mouse oocytes at germinal vesicle (GV) and germinal vesicle breakdown (GVBD) stages were vitrified using open pulled straw (OPS) method. Cumulus cells damage was scored immediately after thawing by double-fluorescent staining. The survival rate of the oocytes was evaluated and the subsequent development of oocytes was assessed through in vitro culture (IVC) and in vitro fertilization (IVF) separately. After vitrification, a higher proportion of cumulus cells of GV oocytes were damaged than those of GVBD and untreated control groups. The survival rate of vitrified GVBD oocytes (94.1%) was significantly higher (p < 0.05) than that of GV oocytes (85.4%). Oocytes vitrified at GVBD stage (55.7%) showed similar cleavage rate compared to those at GV stage (49.2%), but significantly higher (p < 0.05) blastocyst rate (40.9% vs. 27.4%). These results demonstrate that oocytes at GVBD stage remain better cumulus membrane integrity and developmental ability during vitrification than those at GV stage, indicating they are more suitable for immature oocytes cryopreservation in mice.
authors.affiliation: Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing 100093, P.R. China.
authors.forename: Lun
authors.initials: L
authors.lastname: Suo
authors.forename: Guang-Bin
authors.initials: GB
authors.lastname: Zhou
authors.forename: Qing-Gang
authors.initials: QG
authors.lastname: Meng
authors.forename: Chang-Liang
authors.initials: CL
authors.lastname: Yan
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Fan
authors.forename: Xue-Ming
authors.initials: XM
authors.lastname: Zhao
authors.forename: Xiang-Wei
authors.initials: XW
authors.lastname: Fu
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Wang
authors.forename: Qing-Jing
authors.initials: QJ
authors.lastname: Zhang
authors.forename: Shi-En
authors.initials: SE
authors.lastname: Zhu
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000662:veterinary*; D003451:Cryoprotective Agents / Q000494:pharmacology; D054885:Cumulus Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro; D008540:Meiosis; D051379:Mice; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*
chemical_list: D003451:Cryoprotective Agents