Recent Advancements in Vitrification Cryodevices for Gamete and Gonadal Tissue

Abstract

Cryopreservation of gametes and gonadal tissue is nowadays primarily accomplished through vitrification. Variables such as cooling rate, viscosity and volume of vitrification solution are critical in gamete vitrification. In addition, sample size and stepwise exposure are also crucial for gonadal tissue vitrification. Recently a class of cryodevices has been developed to reduce the volume of vitrification solution so as to achieve higher cooling rates. Vitrification devices are classified as "open" or "closed" depending on whether the medium comes into direct contact with liquid nitrogen during the process. Examples of the open cryodevices for gamete vitrification are Cryotop, Cryolock, open pulled straw (OPS), etc., and closed devices are Vitrisafe, CryoTip, and high security vitrification kit. Similarly, for tissue vitrification open cryodevices used are needles, cryovials and closed devices used are Cryotissue, ovarian tissue cryosystem, etc. Among all the gamete cryodevices, Cryotop is unique and the best-selling micro-volume storage device. Use of this device has resulted in the highest number of babies born after embryo or oocyte vitrification. Another novel device, Kitasato vitrification system, is a vitrification solution absorber, which is similar to Cryotop but differs in one way, as it possesses a porous membrane that absorbs extra solution from the gamete. This review provides an update on the recent use of cryodevices for gamete and gonadal tissue vitrification.