Myeloid metaplasia in the spleen after acute haemolysis.

Copper sulphate, phenyl hydrazine and antiserum were administered to adult albino rats to produce equivalent haemolysis. Red pulp activity was studied for myeloid metaplasia after 24, 48 and 72 h, 5 and 7 days. Myeloid metaplasia was not related to the marginal zone proliferation. The activity rose rapidly with all the three agents and followed a similar curve despite the different patterns of haemolysis and erythrophagocytosis. Splenic erythrophagocytosis acts as a powerful feedback for splenic myeloid metaplasia. With copper, the release of reticulocytes and iron binding in haemoglobin is rapid as compared to the other agents, in spite of the initial lag phase, due to its effect on cellular metabolism.