X-Message-Number: 13264 Date: Thu, 17 Feb 2000 15:10:49 -0800 (PST) From: Doug Skrecky <> Subject: polyethylene glycol/DMSO vitrification of oocytes Authors O'Neil L. Paynter SJ. Fuller BJ. Institution Department of Obstetrics and Gynaecology, University of Wales College of Medicine, Heath Park, Cardiff, United Kingdom. Title Vitrification of mature mouse oocytes: improved results following addition of polyethylene glycol to a dimethyl sulfoxide solution. Source Cryobiology. 34(3):295-301, 1997 May. Abstract Oocytes have been successfully cryopreserved using rapid and slow freezing procedures; however, variability in the success of replicates has limited its practical application. We have evaluated the potentially beneficial effects of adding 1 mg/ml of the polymer polyethylene glycol (PEG) (M(r) 8000) to a 6 M dimethyl sulfoxide (Me2SO) vitrification solution. Stepwise addition of cryoprotectant, either with or without PEG, was performed at room temperature (19-21 degrees C). Oocytes were then loaded in plastic insemination straws and held in liquid nitrogen vapour at -140 degrees C for 3 min prior to storage in liquid nitrogen. Oocytes were warmed rapidly to room temperature and removal of cryoprotective agent was effected in the presence of 1 M sucrose solution. Viability was assessed by vitro fertilization. Oocytes cryopreserved after exposure to 6 M Me2SO in the absence of PEG showed 60% normality, 80% fertilization, and 55% development to blastocyst, median of 11 replicate experiments (191 oocytes). Individual replicates yield highly variable survival which ranged from 0 to 100%. The addition of PEG significantly improved oocyte normality to 95% (range 76-100%; median of 9 replicate experiments, 301 oocytes). Rates of fertilization (91%; 60-100%) and development of blastocyst (73%; 67-92) were also improved. The addition of 1 mg/ml PEG to a 6 M Me2SO solution resulted in greatly improved viability of oocytes following cryopreservation and vastly reduced the variability seen with Me2SO solution alone. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=13264