At what age can human oocytes be obtained?

Objective: To determine whether oocyte retrieval and in vitro maturation (IVM) is effective in girls undergoing fertility preservation before cancer treatment. Design: Cohort study. Setting: Tertiary university medical center. Patient(s): Patients ≤20 years old before gonadotoxic chemotherapy undergoing ovarian cortex cryopreservation. Intervention(s): Before ovarian cortex cryopreservation, oocytes in all observed follicles were aspirated, matured in vitro, and cryopreserved. Main Outcome Measure(s): Maturation of oocytes. Result(s): One hundred seventy-nine oocytes were detected in 17/19 patients (89%) aged 5-20 years. We found 7, 8, and 17 oocytes in patients 5, 8, and 10 years old, respectively. The median number of oocytes per patient was 9 (0-37). Maturation rate was 45/133 oocytes (34%). In total, 81 oocytes were cryopreserved. We cryopreserved 4 of 12 detected, 4 of 9 detected, 1 of 8 detected, and 4 of 9 detected IVM oocytes for patients aged 5-10, 11-14, 15-17, and 18-20 years old, respectively. Conclusion(s): Patients undergoing ovarian cryopreservation could benefit from supplementary oocyte aspiration from the cortex. Surprisingly, oocytes were detected even in young premenarcheal girls. The number of oocytes detected, matured, and cryopreserved was not age dependent. Retrieved oocytes can be matured in vitro and cryopreserved. Because no pregnancy has yet resulted from this procedure it should be considered to be experimental. We describe the youngest patients to undergo ovum collection, IVM, and oocyte cryopreservation.