The effect of delayed processing on ovarian tissue stored for fertility preservation

Background. Ovarian tissue cryopreservation (OTC) is important for fertility preservation and conservation. Delay in OTC can occur for transport or workflow management, yet little is understood about the effect of this on the tissue. Objective. To determine if a delay of 24–48 h to OTC affects primordial follicle (PF) health. Methods. Ovaries (n = 6 sheep) were processed immediately or after storage at 4 °C (24 h, 48 h). Tissue was fixed fresh, after cryopreservation or 10-day xenotransplantation. Morphological assessment of follicle health and development was performed. Findings. A total of 1,541 follicles were analysed. A 24 h processing delay did not impact PF health in fresh or cryopreserved tissue. In fresh tissue, a 48 h delay had an adverse effect on PF health (OR = 2.47, 95% CI 1.29–4.71). Interestingly, a 48 h delay resulted in cryopreserved tissue being less likely to be graded as abnormal compared to control (OR = 0.56, 95% CI 0.36–0.87). There was no difference in PF health or development across groups following xenotransplantation. Conclusion. Ovarian tissue can be stored for up to 48 h prior to cryopreservation with no net impact on PF morphology which is indicative of health.