Regeneration Science Takes a Leap Forward (image) Tufts University Share Print E-Mail Caption A limb wound of an adult frog usually leads to the formation of a cartilaginous 'spike' (left). However, treatment with progesterone using a silk hydrogel device for 24 hrs led to the formation of a paddle-like structure (right). (Celia Herrera-Rincon). Credit Source: Allen Discovery Center at Tufts University Usage Restrictions None Share Print E-Mail 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.