This study is an ultrastructural analysis of hemopoiesis in S1/S1d anemic mice. The anemia in this strain is caused by a defect in hemopoietic microenvironment which fails to support hemopoiesis. Marrow cellularity is reduced and vascular channels are dilated. Coverage of sinus endothelium by adventitial cells is nearly twice as in normal mice, suggesting a reduced rate of cell traffic into the circulation. Central macrophages are small with little or no interdigitation with erythroid cells and no crystalloid inclusions as seen in normal littermates. The findings suggest that a fundamental abnormality in the central macrophage may be responsible for the defect in hemopoietic microenvironment.
