Models to crack the code of organ regeneration.

In recent years, there has been a growing, widespread interest in tissue regeneration, with all its medical and social implications, such as, for example, the recovery from illness and wellbeing of humans. Yet, some of the most noticeable features of regeneration were discovered using a purely biological perspective with experimental biology on animal models. We are proud to introduce this Special Issue of The International Journal of Developmental Biology (Int. J. Dev. Biol.) on Regeneration Biology, which is devoted to the different animal models currently used to study regeneration. We also have tailored this Special Issue to include the different achievements that are today the state-of-the art in tissue and organ regeneration. The animal model perspective allows us to identify common and specific traits, summarize the most relevant advances, establish knowledge for the new "kids-on-the-block" and provide a framework to explore the open questions that researchers in the field are pursuing.