Human Ovarian Tissue Slow Freezing

This section provides a detailed description of the protocol for ovarian tissue cryopreservation by slow freezing used at Cliniques Universitaires Saint-Luc in Belgium. The first steps involve preparation of the freezing device, transportation method, and laminar flow workstation in the clean room prior to ovarian biopsy arrival. Ovarian cortex is transferred from the operating room to the clean room at 4 °C and dissected into smaller fragments in sterile conditions. Cortical strips are then placed inside high-security cryotubes prefilled with freezing medium containing DMSO as a cryoprotective agent. The cryotubes are then deposited inside the freezing device, where they are cooled to freezing temperatures. Manual seeding is a crucial step performed at −7 °C, followed by resumption of the freezing protocol at different cooling rates until (−150 °C) is reached. Once the freezing procedure is completed, the cryotubes are transferred for long-term storage in liquid nitrogen.