Slow Freezing of Ovarian Tissue

Slow freezing is the most frequently used method for ovarian tissue cryopreservation. It has been developed to give children and young women who need to undergo gonadotoxic treatments a chance to have their fertility preserved. During the slow freezing, the ovarian cortex can be damaged by ice crystal formation and cell hypertonicity. Addition of cryoprotective agents and use of specific cooling rates protect against cell cryoinjury. Ovarian tissue thawing also represents a challenge, since insufficient removal of cryoprotectants can result to be toxic for cells. Despite the technical challenges, ovarian tissue cryopreservation using slow freezing has proved effective in maintaining the viability of primordial follicles for further transplantation. For this reason, it is no longer considered an experimental procedure.