The proliferation of transplanted haematopoietic cells derived from bone marrow and fetal liver.

The proliferation of transplanted murine haematopoietic cells, derived from the femoral bone marrow of young adults and from the liver on the sixteenth day of gestation, has been compared under standardized conditions. Suspensions of bone marrow cells contained 9-6+/-0-9 CFU per 10(5) cells (sm) and suspensions of fetal liver cells contained 3-7+/-0-5 CFU per 10(5) cells (Sl).Sl/Sm = 0-4. The mean diameter of colonies established by cells derived from bone marrow was 1-3+/-0-3 mm (established mean volume, Vm = 1-2 mm3) and the mean diameter of colonies established by cells derived from fetal liver was 1-7+/-0-1 mm (estimated mean volume, Vl ;-6 mm3). Vl/Vm ;-2. The relationship between the weight of the spleen and the number of bone marrow cells injected into lethally irradiated recipients 10 days previously has been confirmed, and a similar relationship between the weight of the spleen and the number of fetal liver cells injected has been demonstrated. An arbitrarily defined difference of 50 mg between the weight of the spleen in untreated irradiated controls and the weight of the spleen in irradiated recipients of haematopoietic cells has been observed 10 days after the administration of 2-2 x 10(6) bone marrow cells (Dm) or 3-0 x 10(6) fetal liver cells (Dl). Dm/Dl = 0-7. The calculated values of Dm/Dl (relative proliferative capacity), Sl/Sm (relative stem cell content) and Vl/Vm (relative clone size) are in good agreement with the values estimated using the equation Dm/Dl = Sl/Sm x Vl/Vm.