Natures wonders: Virus gene helps human placenta (Introduction)
Found in several animals that use placentas, but not pigs for example: - http://blogs.discovermagazine.com/loom/2012/02/14/mammals-made-by-viruses/
Found in several animals that use placentas, but not pigs for example: - http://blogs.discovermagazine.com/loom/2012/02/14/mammals-made-by-viruses/
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