| Abstract: | Phenylhydrazine treatment of normal mice elicited a rise in the numbers of CFU-S in blood, spleen and liver. High numbers of CFU-S were found in blood and liver 4 d after the first phenylhydrazine injection. CFU-S in the liver decreased slowly and were absent after 2 weeks. Blood CFU-S returned to normal levels by day 6, whereas spleen CFU-S numbers remained high upto day 12 with a 20-fold increase being apparent between days 5 and 8. Bone marrow CFU-S numbers were relatively unaffected except for a dip between days 4 and 7 with a nadir at day 5 where numbers decreased to 50% of the control levels. Approximately 40% of liver, spleen and blood CFU-S present on the 4th d after initiation of phenylhydrazine treatment, were killed with a single dose of hydroxyurea whereas bone marrow CFU-S numbers were not significantly reduced by the drug. Splenectomy performed before (21 d) or during phenylhydrazine treatment did not diminish the number of CFU-S found in theliver on day 4. A 3 d interval was observed between peak numbers of CFS-U and erythroblasts in the liver which suggests that hepatic CFU-S are able to undergo differentiation along the erythroid pathway. The presence of maceophages was correlated with that of erythroblasts in the hepatic central veins. These macrophages may be essential to the liver environment for induction of erythropoiesis. |
