Lee Spievack accidentally cut off his fingertip working on an aeroplane. His brother, a research scientist, sent him powder made up partially out of pig's bladder and told him to sprinkle it on his fingertip. The finger regrew itself in four weeks. How did it work?
Researchers are using materials such as the pig's bladder, which contains something called extracellular matrix, a "mix of protein and connective tissue surgeons often use to repair tendons." By using this stuff, combined with the theory that all parts of the body innately "know" how to repair themselves, you should be able to grow back whole limbs (like The Lizard from Spidey). Amazing stuff. [CBSNews via Boing Boing]