Stem cells' exodus: a journey to immortality.

Stem cell niches provide a regulatory microenvironment that retains stem cells and promotes self-renewal. Recently in Developmental Cell , Rinkevich et al. (2013) showed that cell islands (CIs) of Botryllus schlosseri , a colonial chordate, provide niches for maintaining cycling stem cells that migrate from degenerated CIs to newly formed buds.