Survival and post-warming in vitro competence of human oocytes after high security closed system vitrification
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GAMETE BIOLOGY
Survival and post-warming in vitro competence of human oocytes after high security closed system vitrification N. De Munck & G. Verheyen & L. Van Landuyt & D. Stoop & H. Van de Velde
Received: 23 October 2012 / Accepted: 6 January 2013 # Springer Science+Business Media New York 2013
Abstract Purpose To compare two vitrification methods and two warming methods for human oocyte vitrification using a high security closed device in terms of survival, fertilization and embryo development. Methods For vitrification, oocytes were (1) immediately placed in equilibration solution or (2) they were gradually exposed to the cryoprotectants. For warming, oocytes were placed (1) in a 25 μl preheated (37 °C) thawing solution droplet that was put at room temperature for 1 min once the oocytes were inside or (2) in a 150 μl droplet for 1 minute at 37 °C. Results Survival and preimplantation development were significantly lower when warming was performed in a small preheated droplet. There was no significant difference in survival and embryo development between the gradual or direct exposure to cryoprotectants. Conclusions Using this high security closed vitrification device a 90 % survival rate can be achieved when the oocytes are immediately warmed in a large volume at 37 °C. Keywords Oocyte . Vitrification . Human . Closed straw . Survival . In vitro development Capsule Using a high security closed vitrification device a 90 % survival rate can be achieved when the oocytes are warmed in a large volume at 37 °C. N. De Munck : G. Verheyen : L. Van Landuyt : D. Stoop : H. Van de Velde Centre for Reproductive Medicine, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium N. De Munck (*) : H. Van de Velde Department Reproduction and Genetics, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium e-mail: [email protected]
Introduction Oocyte cryopreservation for women in their reproductive age opens new opportunities in IVF because: (i) it permits women to cryopreserve oocytes prior to gonadotoxic radio-or chemotherapy and ovariectomy [3, 60], (ii) it allows women to delay childbearing [58], (iii) it eliminates donor-recipient endometrium synchronization problems and (iv) it avoids ethical and legal concerns regarding supernumerary cryopreserved embryos and embryo ownership [53]. Since the first report of a pregnancy from a frozenthawed human oocyte in 1986 [11], oocyte cryopreservation has gained increasing interest. Although slow-freezing protocols for oocytes have been modified and improved over time, the outcomes are variable and difficult to reproduce [8, 13, 22, 39, 42, 44, 45, 57, 67]. A consensus has slowly emerged stating that vitrification procedures result in a better embryological and clinical outcome than the slowfreezing procedures [9, 12, 18, 24, 34, 35, 42, 55, 56]. The applied vitrification procedure combines ultra rapid cooling/ warming with high cryoprotectant concentrations and minimal volume methods [29–31]. Hence, the surrounding solution is solidifie
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