The relative spatial distributions of CFU(s) and CFU(c) in the normal mouse femur

Abstract

Femoral bone marrow was divided longitudinally into 2 groups of cells of varying size. By assaying CFU(s) (hemopoietic spleen colony forming cells) and CFU(c) (cells that can form hemopoietic colonies when grown in agar culture) in the 2 zones of the marrow, their distributions across the diameter of the femur was determined. It was shown that the concentration of CFU(s) increased from the femoral axis (15 CFU(s)/105 bone marrow cells) to the bone surface (44 CFU(s)/105 cells), obeying approximately a square law relationship. The CFU(c) concentration increased from the femoral axis (32 CFU(c)/105 cells) to a peak value (260 CFU(c)/105 cells) at about 330 μm from the axis and thence fell off again to the bone surface (77 CFU(c)/105 cells). Selective killing of cells in DNA synthesis using the tritiated thymidine suicide technique, in vivo, showed that CFU(s) near the bone surface proliferated at a faster rate than those more distant from the bone, but that CFU(c) had a fast proliferation rate irrespective of their position in the distribution. Thus, bone marrow cell populations are shown to conform to a well defined spatial organization corresponding to the chronologic relationships between marrow cells.