title: A regulatory mechanism for the number of pluripotential haemopoietic progenitor cells in mice.
abstract: Large changes in the pattern of regeneration of haemopoietic progenitor cells (CFU-S) are reported as a result of simply altering the time interval between administration of certain cytotoxic agents and whole-body irradiation. These results suggest a negative feedback control for the number of CFU-S, which has an appreciable time delay. A high inverse correlation between the number of maturing granulocytic cells (with ring-shaped nuclei) at the time of irradiation and the subsequent regeneration of CFU-S is consistent with these cells producing some substance that controls the number but not the proliferation rate of the CFU-S. The possibility is considered that this mechanism is an important control in the biological regulation of haemopoiesis.
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000528:radiation effects; D003114:Colony-Forming Units Assay; D003520:Cyclophosphamide / Q000494:pharmacology; D005246:Feedback; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL / Q000097:blood; D013997:Time Factors; D014965:X-Rays
chemical_list: D003520:Cyclophosphamide