Peripheral Blood and Hematopoiesis Part 2 Hematopoiesis

Peripheral blood & Hematopoiesis Part 2 Hematopoiesis • • 19761 Objectives of Peripheral blood & Hematopoiesis Part 1 • Examine a blood smear and distinguish each of the formed elements. • Describe the functions of the granulocytes, agranulocytes, platelets, and erythrocytes. • Know the relative cell counts for each of the formed elements in the blood. Part 2 • Describe the normal development of red and white blood cells. Peripheral blood Bone marrow 19761 Bone Marrow 19761 Erythropoiesis McGraw-Hill Companies The cell where hemoglobin appears in the developing erythrocytes is the basophilic erythroblasts (early erythroblast) and takes 4 days to form erythrocytes from stem cells in the bone marrow. McGraw-Hill Companies McGraw-Hill Companies McGraw-Hill Companies McGraw-Hill Companies McGraw-Hill Companies Bone marrow Erythrocyte entering blood vessel 32583 Study Questions 2. Describe the formation of red blood cells, neutrophils and lymphocytes in the bone marrow from their stem cells to their fully differentiated cells. • Erythropoiesis • Takes about 1 week and stimulated by erythropoietin • Originate in bone marrow • Involves major cellular changes • Cell and nuclear volume decrease • Nucleoli diminishes and disappears • Chromatin density increases until nucleus extruded from cell • Decrease in polyribosomes (basophilia) and increase in hemoglobin (eosinophilic) • Mitochondria and other organelles disappear • Steps • 1. Proerythroblast • Large cell with loose, lacy chromatin, nucleoli, and basophilic cytoplasm • 2. Basophilic erythroblast • Strongly basophilic cytoplasm, condensed nucleus, and no visible nucleolus • 3. Polychromatophilic erythroblast • Cell volume is reduced, polysomes decrease, and some cytoplasmic areas fill with hemoglobin producing basophilic and acidophilic regions in cell • 4. Orthochromatic erythroblast • Cell and nuclear volumes continue to condense and no basophilia is evident • 5. Reticulocyte • Cell ejects nucleus to become a reticulocyte, has a small number of polyribosomes • 6. Erythrocyte • Enter blood circulation, lose polyribosomes, and mature as erythrocytes Bone marrow EM 12a marrow EM 8a marrow blood ut 112 Platelets ut 112 Basophilic erythroblast Platelets Proerythroblast ut 112 Late polychromatophilic erythroblast Basophilic erythroblast Platelets Polychromatophilic erythroblast Proerythroblast ut 112 Orthochromatophilic erythroblasts Late polychromatophilic erythroblast Basophilic erythroblast Platelets Polychromatophilic erythroblast Proerythroblast ut 112 Orthochromatophilic erythroblasts Erythrocytes Late polychromatophilic erythroblast Basophilic erythroblast Platelets Polychromatophilic erythroblast Reticulocyte Proerythroblast Red Blood Cell Series Cell Name Size Cytoplasm proerythroblast 16-20 µm basophilic erythroblast (early erythroblast) 12-16 µm polychromatophilic erythroblast 10-16 µm orthochromatophilic erythroblast (late erythroblast, normoblast) 8-10 µm Granules Nucleus deep blue, no hemoglobin none large, round with delicate chromatin, 26 nucleoli tinge of hemoglobin none condensation of chromatin, no nucleoli muddy color none checkerboard pattern no basophilia none dense Granulopoiesis Specific granules first appear in the myelocyte. Granulopoiesis typically takes 10 to 14 days. White Blood Cell Series Cell Name Size Cytoplasm Granules Nucleus myeloblast 15-20 µm sky blue no granules red staining, round, delicate chromatin sky blue non-specific, 1-40 azurophilic granules round to oval, delicate chromatin promyelocyte 15-20 µm neutrophilic myelocyte 17-25 µm some basophilia, some pink few fine neutrophilic granules round to oval, delicate chomatin neutrophilic metamyelocyte 12-16 µm no basophilia, becoming pink many fine neutrophilic granules bean shaped, moderately dense chromatin neutrophilic band or stab 12-16 µm no basophilia, pink many fine neutrophilic granules band or S-shaped eosinophilic myelocyte 13-17 µm some basophilia, specific granules few large eosinophilic granules round to oval, delicate chromatin eosinophilic metamyelocyte 12-16 µm no basophilia, specific granules many large eosinophilic granules bean-shaped, moderately dense chromatin eosinophilic band or stab 12-16 µm no basophilia, specific granules many large eosinophilic granules band or S-shaped EM 12b Neutrophilic myelocyte Neutrophi Reticulocytes ut 112 Platelets Eosinophil or basophil Neutrophilic myelocytes ut 112 Neutrophilic metamyelocytes Neutrophilic metamyelocytes Platelets Eosinophil or basophil Neutrophilic myelocytes ut 112 Neutrophil Neutrophilic metamyelocytes Neutrophilic metamyelocytes Platelets Eosinophil or basophil Neutrophilic myelocytes Granulopoiesis . Takes about 10 to 14 days • Majority of process is dominated by the synthesis of proteins for cytoplasmic granules • Steps 1. Myeloblast • Most immature, finely dispersed chromatin, faint nuclei, and no cytoplasmic 2. Promyelocyte • Basophilic cytoplasm and azurophilic granules being secreted in Golgi apparatus 3. Neutrophilic myelocyte • Specific granules produced in Golgi, moderate number of azurophilic granuloes 4. Neutrophilic metamyelocyte • Specific granules occupy most of cytoplasm, dispersed azurophilic granules, Golgi reduced 5. Neutrophilic band cell • Nucleus is elongated but not yet polymorphic 6. Neutrophil • 3-5 connected lobes, cytoplasm is granulated Maturation of agranulocytes . • All lymphocyte progenitor cells originate in bone marrow and migrate to the thymus or other lymphoid organ (lymph node, spleen, etc.) to proliferate. • Some lymphocytes migrate to thymus, and acquire properties to be T lymphocytes. • Some lymphocytes differentiate into B lymphocytes in the bone marrow and then migrate to peripheral lymphoid organs • Steps • 1. Lymphoblast • Large cells capable of dividing 2-3X to form lymphocytes • 2. Lymphocyte • Maturation= nuclei becomes smaller, nucleoli become less visible, cells decrease in size • Bone marrow= B lymphocyte specialization • Thymus= T lymphocyte specialization • 3. Mature lymphocyte • Larger than newly formed lymphocytes • Acquire distinctive cell surface and other proteins Cardiac stomach w/chronic infection Cardiac stomach w/chronic infection Lung with bronchus and lung – macrophage macrophages EM 8b • macrophage EM 12c in situ bone marrow Megakaryocyte Adipocyte in situ bone marrow Megakaryocytes Adipocytes ne marrow Developing granulated cells Megakaryocytes Lymphocytes Unknown nuclei Lymphocytes Promyelocyte Neutrophilic myelocyte Promyelocyte Neutrophilic myelocytes Neutrophilic metamyelocytes Neutrophilic myelocyte Promyelocyte Neutrophilic myelocytes Neutrophilic metamyelocytes Neutrophilic metamyelocytes Neutrophilic myelocyte Promyelocyte Neutrophilic band cells Neutrophilic myelocytes Neutrophilic band cells Neutrophilic metamyelocytes Neutrophilic band cell Basophilic erythroblast Orthochromatophilic erythroblast Basophilic erythroblast Orthochromatophilic erythroblast Orthochromatophilic erythroblast Reticulocytes Basophilic erythroblast Orthochromatophilic erythroblast Orthochromatophilic erythroblast Reticulocytes Basophilic erythroblast Erythrocytes Orthochromatophilic erythroblast Neutrophilic metamyelocyte Lymphocytes Neutrophilic myelocyte Promyelocyte Unknown nuclei Orthochromatophilic erythroblast Lymphocytes Neutrophilic myelocyte Neutrophilic band Reticulocytes Neutrophilic metamyelocyte Erythrocytes Basophilic erythroblast Orthochromatophilic erythroblast Neutrophilic band Neutrophilic band Neutrophilic metamyelocyte Unknown nuclei Neutrophilic myelocyte Neutrophilic band Neutrophilic metamyelocyte Proerythroblast Orthochromatophilic erythroblast Eosinophils or basophils Orthochromatophilic erythroblast 32583 Bone marrow White blood cell entering a blood vessel