OBJECTIVE: To evaluate the viability of vitrified human germinal vesicle (GV)-oocytes to mature to metaphase II (MII) stage after "rapid" cooling directly in liquid nitrogen in comparison with "slow" cooling in a closed 0.5-mL straw (aseptic system), with or without dimethyl sulfoxide (DMSO) in vitrification solution. The possibility of avoiding parthenogenesis of the oocytes after vitrification using DMSO was investigated. DESIGN: In vitro maturation after vitrification. SETTING: Assisted reproduction centers. PATIENT(S): Patients undergoing standard superovulation treatment and having GV-oocytes after follicular puncture. INTERVENTION(S): The GV-oocytes were vitrified with long/short exposure to DMSO using slow or rapid cooling, then warmed and matured in vitro. MAIN OUTCOME MEASURE(S): Maturation after warming. RESULT(S): Oocyte development up to MII stage after vitrification with DMSO was 71% in the group with "rapid" cooling, and in groups with "slow" cooling, 68% and 72% for long and short exposure to DMSO, respectively. The maturation rate of GV-oocytes after slow cooling without DMSO was 51%. In the vitrification with long-term contact of oocytes with DMSO group, a high rate of parthenogenesis was observed. When vitrification with short-term contact of oocytes with DMSO at room temperature was used, no parthenogenesis was observed. CONCLUSION(S): Cryopreservation of human GV-oocytes in open-pulled straws OPS) using an aseptic slow cooling method gives high maturation rates but only in combination with DMSO. To avoid spontaneous parthenogenesis, the exposure to DMSO must occur for a reduced time and at room temperature.
ASEPTIC VITRIFICATION OF HUMAN GERMINAL VESICLE OOCYTES USING DIMETHYL SULFOXIDE AS A CRYOPROTECTANT / Isachenko, V; Montag, M; Isachenko, E; Dessole, Salvatore; Nawroth, F; VAN DER VEN, H.. - In: FERTILITY AND STERILITY. - ISSN 0015-0282. - 85(3):(2006), pp. 741-747.