X-Message-Number: 13271
Date: Fri, 18 Feb 2000 17:46:04 -0800 (PST)
From: Doug Skrecky <>
Subject: polyethylene glycol and blastocyst vitrification

  Ohboshi S.  Fujihara N.  Yoshida T.  Tomogane H.
  Department of Animal Science, Nippon Veterinary and Animal Science
  University, Tokyo, Japan. 
  Usefulness of polyethylene glycol for
  cryopreservation by vitrification of in vitro-derived bovine
  Animal Reproduction Science.  48(1):27-36, 1997 Jul.
  A series of five experiments measured the high survival of bovine blastocysts
  produced in vitro after cryopreservation by vitrification.
  The vitrification solution (designated VS) contained 40% (v/v) ethylene
  glycol, 6% (w/v) polyethylene
  glycol and 0.5 M sucrose in phosphate-buffered saline.
  Embryos developed in vitro at Days 7 and 8 (Day 0 = insemination day) were
  exposed in one step to VS for 1 min or two steps with 10% ethylene
  glycol for 5 min and then VS for 1 min. In both cases, the
  embryos were finally cryopreserved in liquid nitrogen. After the embryos were
  warmed rapidly and the VS solution diluted, the survival rates were assessed
  by monitoring hatching rate in vitro. They were 13.0% for the one-step and
  72.7% for the two-step procedures (P < 0.001). When embryos were exposed to
  individual solutions containing 6% (w/v) of each of 4 macromolecules
  (polyethylene glycol, BSA,
  polyvinylpyrrolidone or Ficoll) in the two-step protocol and then
  cryopreserved, the survival rates were 79.3, 34.8, 41.4 and 57.1%,
  respectively. After embryos had been exposed to the VS in two steps and then
  cryopreserved, there were no significant differences in survival rates when
  the solutions were diluted with or without sucrose. These results indicated
  that a vitrification solution containing polyethylene
  glycol can be used for cryopreservation of
  bovine blastocysts produced in vitro, and that a two-step addition of VS
  improved the in vitro survival of post-warming embryos. It was also shown to
  be possible to dilute post-warming embryos directly without the use of
  sucrose solution.

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