1 Introduction.- 2 Fundamental Control of Hematopoiesis.- A. Introduction.- B. Hierarchical Organization of Hematopoietic Cells.- C. Assay and Characterization of In Vitro Clonogenic Cells.- D. Use of In Vitro Clonogenic Cell Assays.- E. Newer Assays for More Primitive Cells.- F. Regulatory Mechanisms.- G. Future Outlook.- References.- 3 Kidney Regulation of Erythropoietin Production.- A. Introduction.- B. Model for the Control of Erythropoietin Production.- C. Hypoxia and Erythropoietin Production.- D. Adenosine and Erythropoietin Production.- References.- 4 The Mechanism of Action of Erythropoietin: Erythroid Cell Response.- A. Introduction.- I. The Erythropoietin Gene.- II. The Erythropoietin Molecule.- III. Erythropoietin-Responsive Cells.- IV. The Erythroid Burst-Forming Unit.- V. The Colony-Forming Unit Erythroid.- B. Model Systems for Studying the Interaction of Erythropoietin with Erythroid Progenitor Cells.- I. The Erythropoietin Receptor.- C. Interaction of Other Growth and Development Factors with Erythroid Progenitor Cells.- D. The Erythroid Differentiation Program.- I. Gene Expression During Erythroid Cell Differentiation.- E. Signal Transduction in Erythroid Progenitor Cells.- F. Erythropoietin as a Competence or Progression Factor.- G. Conclusion.- References.- 5 The Arachidonic Acid Cascade and Erythropoiesis.- A. Introduction.- I. Background.- II. Classification of Eicosanoids and Their Chemistry.- 1. Prostaglandins.- 2. Thromboxanes.- 3. Hydroperoxy/Hydroxy Fatty Acids.- 4. Leukotrienes.- 5. Diglyceride, Phosphatidic Acid, and Lysophosphatidic Acid.- III. Erythropoiesis and Eicosanoids.- B. Evidence for the Roles of Arachidonic Acid Metabolism in Erythropoiesis.- I. Criteria for Implicating Eicosanoids.- II. Target Cell Responses.- III. Cell-Cell Interactions.- IV. Specific Involvement of the Lipoxygenase Pathway.- C. Future Directions for Research.- References.- 6 Iron Deficiency and Megaloblastic Anemias.- A. Iron-Deficiency Anemia.- I. IntroductlcÁ