“Not only does the system need to figure out where the damage was, it then needs to store that information for months,” said Michael Levin, a biologist at Tufts University. “Then, when the new growth comes out, it needs to communicate information to be read by the bone cells.”

Researchers don’t know where this information is stored. But Dr. Levin is trying to understand the phenomenon by studying planarian flatworms. They are known for their extraordinary regenerative abilities; chop one into several pieces, and each will grow a head and tail.

Eventually, scientists hope to apply what they learn to humans. “If we have the ability to tell cells what to build and when to stop,” Dr. Levin said, “most problems in biomedicine would go away.”

(http://www.autoadmit.com/thread.php?thread_id=5917330&forum_id=2#50222058)