The results of the first full-scale clinical trial using grafts of fetal tissue to treat Parkinson's disease were recently published and, as we briefly note in our 'In the news' column, public reactions have already appeared. Not surprisingly, a significant part of the discussion has centred on the implications of using human tissue for this therapeutic procedure. This aspect of the problem impinges directly on a related topic that is hotly debated in many countries: the use of human stem cells for research purposes. Neuroscientists have not shied away from the study of stem cells and significant effort has been made to identify and characterize them. But what is a neural stem cell? This question is at the core of the Perspective article from Arturo Alvarez-Buylla and his colleagues in this issue. In this article, they review the characteristics of adult neural stem cells, explore their relationship to embryonic neuroepithelial cells and propose a hypothesis aimed at unifying their lineages. Their idea is likely to have a profound impact on our thinking about neural stem cells and might also lead us to revisit our definition of glial cells.

This issue also represents a milestone for Nature Reviews Neuroscience . Following his appointment as Publisher of Nature Reviews, Peter Collins leaves our editorial team. As Peter's influence on the development of this journal has been profound, it is only fair to thank him for his labour and to wish him luck in his new position. The good news, however, is that Rachel Jones has now joined our team. Rachel's background on systems and cognitive neuroscience and her editorial experience at Nature is a fantastic addition to the journal and her arrival is certainly cause for celebration. So, thank you Peter, and welcome Rachel.