ietic stem cells really have to go through a series of progenitor differentiation steps to produce blood cells? Apparently, not always. Yamamoto R, Morita Y, Ooehara J et al. Cell 2013 Aug; 154:1112-26 <http://webr.emv2.com/faculty1000/F1000_Monthly_images/spacer.gif> F1000Prime Reports <http://webr.e