Heads or tails? Scientists identify gene that regulates polarity in regenerating flatworms

When cut, a planarian flatworm can use a population of stem cells called neoblasts to regenerate new heads, new tails or even entire new organisms from a tiny fragment of its body. Mechanisms have been sought to explain this process of regeneration polarity for over 100 years, but until now, little was known about how planaria can regenerate heads and tails at their proper sites.