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@ DEFINITION, , Erythropoiesis, , @ SITE OF ERYTHROPOIESIS, , @ IN FETAL LIFE, , m@ IN NEWBORN BABIES, CHILDREN AND ADULTS, m@ PROCESS OF ERYTHROPOIESIS, , @ STEM CELLS, , @ CHANGES DURING ERYTHROPOIESIS, @ STAGES OF ERYTHROPOIESIS, @ FACTORS NECESSARY FOR ERYTHROPOIESIS, , @ GENERAL FACTORS, @ MATURATION FACTORS, , @ FACTORS NECESSARY FOR HEMOGLOBIN FORMATION, , @ DEFINITION, , Erythropoiesis is the process of the origin,, development and maturation of erythrocytes., Hemopoiesis is the process of origin,, development and maturation of all the blood, cells., , @ SITE OF ERYTHROPOIESIS, @ IN FETAL LIFE, , In fetal life, the erythropoiesis occurs in different, Sites in different periods:, , 1. Mesoblastic Stage, , During the first two or three months (first, trimester) of intrauterine life, the RBCs are, Produced from mesenchymal cells of yolk sac., , 2. Hepatic Stage, , During the next three months (second trimester), of intrauterine life, RBCs are produced mainly, from the liver. Some cells are produced from the, spleen and lymphoid organs also., , 3. Myeloid Stage, , During the last three months (third trimester) of, intrauterine life, the RBCs are produced from red, bone marrow and liver., , @ IN NEWBORN BABIES, CHILDREN, AND ADULTS, , 1. Up to the age of 20 years: RBCs are, produced from red bone marrow of all bones, , 2. After the age of 20 years: RBCs are, produced from all the membranous bones, and ends of long bones., , LL ————