Ovarian tissue vitrification as a method for fertility preservation: A study of follicle number and morphology after vitrification

Purpose: The aim was to evaluate the effects of ovarian cortex vitrification on follicle number and morphology. Materials and Methods: We excised approximately 5 mm of ovarian tissue from one ovary of each of 10 reproductiveaged women who underwent surgery for the removal of benign ovarian tumors. A cryoprotectant agent containing 7.5%dimethylsulphoxide and 7.5% ethylene glycol was added to the ovarian cortex. Post-vitrifi cation ovarian cortex was placed in aCryotissue device and frozen in liquid nitrogen. We evaluated the shape and number of the follicles as well as the granulosa celllayers. The quality of the follicles was evaluated based on the morphological integrity of the oocytes, granulosa cells, and basalmembranes as determined by hematoxylin and eosin staining. Results: The median age of the patients was 33 years (range:28-40 years). The mean number of follicles per patient was 17 ± 7. After thawing, 59 primordial follicles (35.3%), 45 (26.9%)primary follicles and 6 (3.5%) secondary follicles were retrieved. The remaining follicles (34.1%) were atretic. There was asignifi cant relationship between number of follicles and age (P = 0.012, r = −0751). No differences were found in the morphologyof the granulosa cells, stroma or collagen in both groups. The number of primordial follicles, primary follicles, secondary follicles,and follicular atresia were not signifi cantly different before and after vitrifi cation. Conclusion: In our study, vitrifi cation doesnot cause signifi cant changes to the morphology and number of follicles.