The relative spatial distribution of erythroid progenitor cells (BFUe and CFUe) in the normal mouse femur.

Femoral mouse bone marrow cells were separated into axial and marginal fractions, in order to investigate the relative concentration of erythroid progenitor cells (BFUe and CFUe) with respect to their location across the diameter of the femur. Two areas of high incidence of early progenitor cells (BFUe) were identified: one lying near the bone surface with a peak at about 410 micrometers radial distance from the axis of the bone; the other nearer the centre of the bone with a peak at about 270 micrometers. The more immature BFUe were found in higher proportion in the marginal peak. In contrast, CFUe, apart from very low concentration values in the vicinity of the bone surface, demonstrated a fairly uniform distribution throughout the marrow. The present results indicate that the distribution of erythroid progenitor cells within the bone marrow is not random. The haemopoietic tissue seems to exhibit a well-defined structure that may be relevant in regulating proliferation and differentiation processes.