[Medullary and extramedullary hematopoiesis in the dog after whole body irradiation and transfusion with stem cells obtained from blood].

Autologous transfusion of 2.8-39.5 X 10(9) cryopreserved mononuclear blood leukocytes (BMNC) into 1200 R wholebody irradiated dogs leads within 10 days of irradiation and transfusion to patterns of hemopoietic regeneration of bone marrow, spleen and blood the extent of which correlates with the number of granulocytic progenitor cells, measured as CFU-C, in the tranfusate. In the marrow there are erythrocytic, granulocytic and megakaryocytic foci of regeneration ("colonies") in a proportion of 10:6:1 respectively, while the spleen exhibits cell dose related regeneration of the white pulp and a (transitory) erythropoietic wave of regeneration localized in the red pulp only. The mechanisms of the development of this extramedullary hemopoiesis are unknown. However, it closely resembles the prenatal phase of splenic erythropoiesis which disappears soon after birth. The normoblasts present in the blood at day 10 after irradiation and transfusion of BMNC correlate with extramedullary blood cell formation buy not with the type and extent of bone marrow regeneration.