Ovarian tissue cryopreservation and transplantation is the only fertility preservation option that enables both restoration of fertility and resumption of ovarian endocrine function, avoiding the morbidity associated with premature menopause. It is also the only technique available to prepubertal patients and those whose treatment cannot be delayed for life-threatening reasons. Ovarian tissue cryopreservation can be done in two different ways, either as ovarian cortical fragments or as a whole organ with its vascular pedicle. Although use of cortical strips is the only procedure that has been approved by the American Society for Reproductive Medicine, it is fraught with drawbacks, the major one being serious follicle loss occurring after avascular transplantation due to prolonged warm ischemia. Whole ovary cryopreservation involves vascular transplantation, which could theoretically counteract the latter phenomenon and markedly improve follicle survival. In theory, this technique should maintain endocrine and reproductive functions much longer than grafting of ovarian cortical fragments. However, this procedure includes a number of critical steps related to (A) the level of surgical expertise required to accomplish retrieval of a whole ovary with its vascular pedicle, (B) the choice of cryopreservation technique for freezing of the intact organ, and (C) successful execution of functional vascular reanastomosis upon thawing. The aim of this systematic review is to shed light on these challenges and summarize solutions that have been proposed so far in animal experiments and humans in the field of whole ovary cryopreservation and transplantation.

The review follows the following plan: 

1. Introduction
2. Methodology
3. Challenges & Solutions
   1. Whole Ovary Removal
   2. Freezing of a Whole Ovary
      1. Freezing Challenges
      2. Freezing Solutions
   3. Vascular Transplantation of a Whole Ovary
      1. Vascular Transplantation Challenges
      2. Vascular Transplantation Solutions
4.  What Has Been Done in Humans So Far?
   1. 1. Fresh Whole Ovary Transplantation
      2. Whole Ovary Removal with a View to Cryopreservation
      3. Cryopreservation of the Human Ovary
      4. Recipient Pedicle Selection for Vascular Transplantation
5. Limitations
6. Conclusions

This entry is adapted from the peer-reviewed paper 10.3390/jcm9103196