Alexander Maximow, a great visionary in hematopoiesis. He introduced the “unitarian theory of hematopoiesis”^{22, page 538} (ie, “common stem cell for all blood elements”^{22, page 545}) and pioneered other concepts about stem cells and their microecological niches within BM stroma. Photograph reprinted from Konstantinov IE, In Search of Alexander A. Maximow: The Man Behind the Unitarian Theory of Hematopoiesis, Perspectives in Biology and Medicine. Vol. 43. Winter 2000:269-276, with permission of Special Collections Research Center, University of Chicago Library.