Background: The aim of this study was to assess the immediate post-thawing injury to the human ovary that was cryopreserved either as a whole with its vascular pedicle or as ovarian cortical strips.
Materials and methods: Bilateral oophorectomy was performed in two women (46 and 44 years old) undergoing vaginal hysterectomy and laparoscopic hysterectomy, respectively. Both women agreed to donate their ovaries for experimental research. In both patients, one of the harvested ovaries was sectioned and cryopreserved (by slow freezing) as ovarian cortical strips of 1.0 x 1.0 x 5.0 mm(3) each. The other ovary was cryopreserved intact with its vascular pedicle. After thawing 7 days later, follicular viability, histology, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick-end labelling (TUNEL) assay (to detect apoptosis) and immunoperoxidase staining (to define Bcl-2 and p53 protein expression profiles) of the ovarian tissue were performed. Tissues from non-cryopreserved ovaries served as control specimens (two cases).
Results: The overall viability of the primordial follicles was 75 and 78% in intact cryopreserved-thawed (C-T) ovaries and 81 and 83% in ovarian cortical strips in the 46- and 44-year-old patients, respectively. Comparable primordial follicle counts, absence of features of necrosis, mean values of apoptosis and weak Bcl-2 and p53 protein expressions were observed both in the intact C-T ovary and in the C-T ovarian cortical strips.
Conclusions: Cryoperfusion and cryopreservation of entire human ovary can be achieved with the maintenance of excellent viability of the superficial and the deeper tissues using a slow-freezing protocol. Cryopreservation injury is associated neither with significant alteration in the expression pattern of Bcl-2 and p53 proteins in the ovarian tissues nor with significant follicular damage.