On the cover: Human embryonic stem cells colonies generate hematopoietic zones upon transfer on OP9 feeder layers. These hematopoietic zones are endothelium-lined structures containing round CD34⁺CD43⁺ hematopoietic precursor cells. Transfer of such zones on Delta-ligand 1-expressing OP9 cells results in differentiation to mature T cells. Timmermans, F., I. Velghe, L. Vanwalleghem, M. De Smedt, S. Van Coppernolle, T. Taghon, H. D. Moore, G. Leclercq, A. W. Langerak, T. Kerre, J. Plum, and B. Vandekerckhove. 2009. Generation of T cells from human embryonic stem cell-derived hematopoietic zones. J. Immunol. 182: 6879–6888.