Adherent stem cells: frequency in mouse marrow and terminal clone sizes in long-term culture

Adherent stem cells (ASC) are hematopoietic stem cells of the mouse bone marrow that are equivalent to CFU-S in pluripotency (they produce CFU-S) and proliferative ability (they go through up to 25 doublings). They can be assayed in vitro by a limiting dilution overlay technique in which stromal bone marrow long-term cultures serve as underlayers. In this article we estimate the occurrence rates of ASC in fresh and adherent bone marrow cells and report the distribution of population doublings estimated for 152 ASC clones.