The bone marrow cavity contains different types of hematopoietic and nonhematopoietic progenitors.

HSC indicates hematopoietic stem cells; MSC, mesenchymal stem cells; AnBl, angioblasts. The boxes represent “drawers” that indicate differentiation potential. Colors within the drawers indicate tissue conversions that have been described or postulated (question marks). The presence of angioblasts in the bone marrow is speculative. Additional types of precursors may also exist.