Table 1. Comparison of slow freezing and vitrification method.

CPA: cryoprotective agents

Characteristics	Slow freezing	Vitrification
Sample volume (uL)	100-250	1-2
Working time	More than 3 hours	Fast less than 10 min.
Cost	Expensive	Comparatively cheaper
Concentration of CPAs	Low	High
Risk of toxicity of CPAs	Low	High
Manipulation skills	Easy	Difficult
Past thaw viability	High	High
Status of system	Closed system only	Opened or closed system