OBJECTIVE: Evaluating the developmental competence of immature oocytes collected from surplus medulla tissue in connection with ovarian tissue cryopreservation for fertility preservation.

DESIGN: Cohort comparative study.

SETTING: University laboratory in Denmark from 2011-2012.

POPULATION: 69 girls and women (0-38 years of age) who each had one ovary cryopreserved for fertility preservation.

METHODS: Ovaries were obtained directly from the local hospital or from collaborating hospitals (two to five hours' transport on ice). Immature oocytes were aspirated from large antral follicles visible on the ovaries, and collected from the saline solution, containing surplus medulla tissue, following dissection of the ovarian cortical tissue for cryopreservation. The immature oocytes were cultured for 48 h in an Embryoscope™ Time-lapse System or in culture dishes overlaid with liquid paraffin using commercial and in-house supplemented culture media.

MAIN OUTCOME MEASURES: Maturation rate for immature oocytes reaching metaphase II.

RESULTS: With a maturation rate of 3.1%, only 21 of 682 immature oocytes reached metaphase II. Immature oocytes from ovaries that had been transported on ice for two to five hours performed significantly poorer than those recovered immediately after surgery. Addition of epidermal growth factor and follicle fluid from human small antral follicles to the culture medium did not augment the maturation rate. Immature oocytes cultured in the Embryoscope performed significantly better than those in conventional culture dishes.

CONCLUSIONS: In vitro maturation of immature oocytes should only be attempted clinically from visible antral follicles and where the ovary is not subjected to a cooling period prior to recovery of immature oocytes.