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

Abstract

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 reproductive aged 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-vitrification ovarian cortex was placed in a Cryotissue device and frozen in liquid nitrogen. We evaluated the shape and number of the follicles as well as the granulosa cell layers. The quality of the follicles was evaluated based on the morphological integrity of the oocytes, granulosa cells, and basal membranes 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 a significant relationship between number of follicles and age (P = 0.012, r = −0751). No differences were found in the morphology of the granulosa cells, stroma or collagen in both groups. The number of primordial follicles, primary follicles, secondary follicles, and follicular atresia were not significantly different before and after vitrification. Conclusion: In our study, vitrification does not cause significant changes to the morphology and number of follicles.