While research has uncovered many details about how blood cells function within bone marrow, the work of other cells existing in that space has remained a relative mystery. Now, researchers from the Perelman School of Medicine at the University of Pennsylvania and Children's Hospital of Philadelphia (CHOP) have published a "bone marrow atlas" in Cell that provides a first-of-its-kind, full view of all the cells existing within it, offering a better understanding of both healthy and diseased blood production.