The Paradoxical Dynamism of Marrow Stem Cells: Considerations of Stem Cells, Niches, and Microvesicles 3 Z# A- b3 i0 j* U % g7 }1 G% V; X6 R; U. v {https://springerlink.metapress.com/content/056w7n5633106010/resource-secured/?target=fulltext.pdf&sid=ieorinvt3qpqtz453d2k2urg&sh=www.springerlink.com