Structure and connectivity of the hematopoietic landscape. (A) Schematic representation shows cell populations with various differentiation potentials on the Waddington landscape. The panels on the right show how different levels with local minima correspond to attractor states and transition likelihoods (indicated by arrow width). (B) The degree of connectivity between HSPC subpopulations is not yet fully understood. Under transplantation settings, lineage commitment is established in some HSCs and maintained in downstream progenitors, forming multiple tracks of differentiation (left). The landscape of steady-state hematopoiesis may allow for more transitions and HSPC fate plasticity (right). MPP, multipotent progenitor.