title: The sensitivity of G0-state haemopoietic spleen colony-forming cells to a stimulus for proliferation.
abstract: Haemopoietic spleen colony-forming units (CFU-s) close to the axis (axial CFU-s) of the long bones have a high probability of self-renewal. They are pluripotent cells and are largely in a G0-State. By contrast, CFU-s close to the bone surface (marginal CFU-s) have a lower probability of self-renewal and are probably more mature, though still pluripotent. Most CFU-s proliferation arises in this zone. As a consequence, marginal CFU-s tend to have shorter G0 histories than do axial CFU-s. Femoral marrow was, therefore, divided into axial and marginal populations and the sensitivity of the CFU-s to an endogenous CFU-s-specific proliferation-stimulating factor was assessed and compared by the tritiated thymidine suicide technique. It was found that axial CFU-s are considerably more resistant to stimulation than are marginal CFU-s in that larger doses for longer periods of exposure are required to increase the proliferative activity of the cells. This behaviour is consistent with the suggestion that cells with a low division probability exist in deeper levels of the quiescent G0-state. Although this hypothesis was developed from the behaviour of cells maintained in culture under sub-optimal physiological conditions, this phenomenon appears, in vivo, to be a characteristic of the stem cell population of haemopoietic tissue; their high resistance to stimulation maintaining the axial CFU-s in a quiescent state.
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000378:metabolism; D001854:Bone Marrow Cells; D002455:Cell Division; D002470:Cell Survival; D003114:Colony-Forming Units Assay; D003470:Culture Media; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D007399:Interphase; D008297:Male; D051379:Mice; D013154:Spleen / Q000166:cytology*; D013936:Thymidine / Q000378:metabolism
chemical_list: D003470:Culture Media; D013936:Thymidine