Clin Exp Reprod Med.  2013 Dec;40(4):148-154. 10.5653/cerm.2013.40.4.148.

Closed vitrification of mouse oocytes using the CryoLogic vitrification method: A modification that improves developmental competence

• Jo JW
• Jee BC
• Suh CS
• Kim SH

• KMID: 2167492
• DOI: http://doi.org/10.5653/cerm.2013.40.4.148

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.
CONCLUSION
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.

Keyword

Vitrification; Closed method; Open method; Oocyte; Spindle

MeSH Terms

Animals
Apoptosis
Blastocyst
Blastomeres
Embryonic Development
Female
Humans
Mental Competency*
Methods
Mice*
Oocytes*
Pregnancy
Vitrification*