X-Message-Number: 28307
From: "Basie" <>
Subject:  Freezing  Pig Embryos
Date: Wed, 9 Aug 2006 21:56:13 -0400

Researchers Report Technique For Freezing And Preserving Genetically 
Enhanced Pig Embryos
Researchers led by a University of Missouri-Columbia professor of 
reproductive biotechnology have reported success in freezing and preserving 
swine embryos that were created by in vitro techniques and that carried 
modified genetic material. After thawing and transfer to a surrogate mother, 
some of the embryos went on to produce live piglets with new genetic traits.
In a paper posted today (May 3, 2006) on the Web site of Biology of 
Reproduction--Papers in Press, a team headed by Dr. Randall Prather, 
co-director of the National Swine Resource and Research Center, note that 
their technique could prove valuable in allowing genetically enhanced swine 
to be transported as embryos across the country and throughout the world.

Because many embryos are needed to produce a successful pregnancy in 
surrogate female pigs, this new procedure will enable workers to collect an 
adequate number of altered embryos and store them until they can be 
transplanted to a surrogate.

Swine embryos have been difficult to freeze and preserve because of their 
sensitivity to cold due to a high level of lipids in the cells of the 
embryos. It was expected that it would be even more difficult to freeze and 
preserve swine embryos that had been produced by in vitro methods.

Dr. Prather's team overcame the obstacles to freezing swine embryos by first 
removing lipids from unfertilized eggs before fertilizing them with muscle 
cells from a male pig containing modified genetic material. The resulting 
embryos were then frozen at the blastocyst stage.

Upon thawing, embryos were transferred to surrogate female swine. Embryos 
placed in the oviducts of two surrogates led to pregnancies that produced 
two piglets in one litter and eight piglets in another.

Testing confirmed that the piglets carried the modified genetic material and 
that the new gene had altered the fatty-acid content in tissues from the 

With ten piglets from 163 frozen and preserved embryos, the researchers feel 
that their procedure appears to work well, although further studies will be 
needed to refine the technique.

Dr. Prather and his team expect that freezing and preserving swine embryos 
will enable wide dissemination of swine with genetic traits that are 
commercially valuable and also important for biomedical research involving 
this increasingly relevant animal model for human disorders.

Biology of Reproduction, published by the Society for the Study of 
Reproduction, is the top-rated peer-reviewed research journal in the field 
of reproductive biology.

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