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Oocyte cryo-banking by means of the Cryotop vitrification method represents a viable option for healthy women, producing excellent survival rates and a clinical outcome similar to that obtained with fresh oocytes. This approach could potentially be used in cancer patients who want to safeguard their fertility. Cancer patients could potentially benefit from this approach by storing their oocytes before the onset of the oncological therapy.

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The aim of this study was to evaluate the impact of different cryopreservation protocols on the repolymerization of metaphase (M)II spindles in human oocytes. Fresh aspirated donor oocytes were cryopreserved 3-4 h after retrieval using four different protocols: slow freezing using 1.5 mol/l 1,2-propanediol (PROH) + 0.2 mol/l sucrose (n = 36); 1.5 mol/l PROH + 0.3 mol/l sucrose (n = 34); 1.5 mol/l PROH + 0.3 mol/l sucrose with Na(+) depleted-choline replaced media (n = 27), and vitrification by the Cryotip method (n = 23). The control group comprised 34 fresh oocytes. Three hours after thawing, surviving and control oocytes were fixed for meiotic spindle/chromatin assessment. Survival rates were 63.8, 73.5, 74.1 and 86.9% respectively for the four protocols described above. Survival for vitrified oocytes was higher than that observed for slow freezing with 0.2 and 0.3 mol/l sucrose (P < 0.05). The proportion of oocytes showing normal spindle configuration was similar for the four protocols (81, 73.9, 88.9 and 81.3% respectively) and 88.5% for controls, showing that the MII spindle returns to its normal configuration after 3 h of post-thawing incubation under standard conditions, irrespective of the cryopreservation technique used.