Cover picture: Embryonic stem cell-derived neurons incorporated into the hypothalamus 3 weeks after intrauterine transplantation into the cerebral ventricles of embryonic rats. Engrafted donor cells were identified by immunofluorescence with an antibody to enhanced green fluorescent protein and visualized with the help of a fluorescence microscope. For details, see the article by Wernig et al. in this issue (pages 5257–5268).