X-Message-Number: 13264
Date: Thu, 17 Feb 2000 15:10:49 -0800 (PST)
From: Doug Skrecky <>
Subject: polyethylene glycol/DMSO vitrification of oocytes

  O'Neil L.  Paynter SJ.  Fuller BJ.
  Department of Obstetrics and Gynaecology, University of Wales College of
  Medicine, Heath Park, Cardiff, United Kingdom.
  Vitrification of mature mouse oocytes: improved results following addition of
  polyethylene glycol to a dimethyl sulfoxide
  Cryobiology.  34(3):295-301, 1997 May.
  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.

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