Concentration gradient of blood stem cells in mouse bone marrow--an open question.

The distribution of pluripotential blood stem cells (CFU-S) in bone marrow was studied in four strains of mice. Analyses of paired samples containing various fractions of axial and marginal bone marrow cells, as well as longitudinal 200-micrometer sections, revealed a rather uniform spatial distribution of CFU-S across the diameter of the femoral medullary cavity, in contrast to the finding by others of a CFU-S concentration gradient extending from the endosteum to the central longitudinal axis of bone marrow. The existence of a stem cell gradient is therefore open to question.