Adult stem cells reside in most parts of the body where high tissue turn-over is evident. However there are vastly different demands on the number of cells that might be produced and no better examples of each extreme are the neurogenic zones of the brain, and the crypt compartments of the intestines. From a perspective of understanding the function of the transcription factor Myb, we have explored the biology of stem cell niches in both these radically different tissues. Each tissue has remarkable features, provide different in vivo and in vitro options for manipulation and open up novel insights into damage responses and diseases like cancer. A variety of studies using mouse models, conditional and hypomorphic Myb mutants, radiation induced damage and primary in vitro assays have advanced our understanding of both stem cell niches and has revealed a previously unrecognised role for Myb in the regulation of stem cells.