 Cells identical in appearance come both from a myeloid lineage (referred to as myeloid dendritic cells) and also from a lymphoid lineage (referred to as plasmacytoid dendritic cells).The development and regulation of DC is not well-characterized.While the DC precursors have been identified in the human fetal liver, thymus, and bone marrow, during adult life DC are thought to be produced only from the bone marrow and released into the blood to wander and settle down.