The number of these cells injected into irradiated mice is proportional to the number of discrete splenic nodules that formed in experiments demonstrating their existence by Till and McCulloch. John Dick identified a subpopulation of these cells in tumors that initiate relapse, called their “cancer” type. These cells are maintained in intestinal (10[1])crypts and other eponymous “niches.” (10[1])Genes like Nanog and Oct4 are among the factors named for Yamanaka (10[1])that “induce” (10[1])somatic cells to become these cells. (10[1])Patients receive the hematopoietic type (10[1])of these (10[1])cells in a bone marrow (10[1])transplant. The self-renewal capacity and pluripotency of these cells make them a common research topic in regenerative medicine. For 10 points, (10[1])name these cells that can differentiate into various other cell types. ■END■