title: Closed vitrification of mouse oocytes using the CryoLogic vitrification method: A modification that improves developmental competence.
abstract: OBJECTIVE
  To compare the mouse oocyte vitrification outcomes of the CryoLogic vitrification method (CVM) and the conventional open method using a Cryotop. Two CVM methods (original CVM and modified CVM) were tested.
  
  
  METHODS
  Mature oocytes obtained from female BDF-1 mice were vitrified by two-step exposure to equilibrium and vitrification solutions. Three vitrification protocols were tested on three groups: the CVM-kit, modified CVM, and Cryotop groups. After exposure to the two solutions, the oocytes were vitrified. After warming, the oocytes were fertilized in vitro, and the embryo development was assessed. Blastomeres positive for caspase were counted using an in situ assay kit. The spindle morphology and chromosome configurations of warmed vitrified oocytes were also assessed.
  
  
  RESULTS
  The modified CVM and Cryotop groups showed similar developmental capacities, and similar proportions of cells with intact spindles and chromosome configurations. The modified CVM protocol was superior to the original CVM protocol for developmental competence and intact spindle preservation. However, the CVM group showed a relatively higher number of apoptotic cells in blastocysts.
  
  
  CONCLUSIONS
  Closed vitrification using the modified CVM protocol may be used as an alternative to the conventional open method, but strategies to decrease apoptosis in the blastomere need to be investigated.
authors: Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea. ; Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea. ; Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Seoul, Korea.
authors: Jun Woo
authors: JW
authors: Jo
authors: Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea. ; Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
authors: Byung Chul
authors: BC
authors: Jee
authors: Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea. ; Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
authors: Chang Suk
authors: CS
authors: Suh
authors: Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea. ; Department of Obstetrics and Gynecology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors: Seok Hyun
authors: SH
authors: Kim
keywords: Closed method; Oocyte; Open method; Spindle; Vitrification