Schmidtea Mediterranea Showing Regrowth (image) PLOS Caption The animal on the left is a normal worm that successfully regenerated a head and tail (white/unpigmented tissue). In the animal on the right, the zic-1 gene was inactivated, which prevented head regeneration. Credit Dr Christian Petersen (firstname.lastname@example.org) Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.