1. Chapter 6 Hematopoiesis
Hematology Unit 2
Chapter 6
Hematopoiesis
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2. Hematopoiesis The production of blood cells and platelets
Whole blood is composed of fluids and cells
Plasma – fluid portion
Cells – RBCs, WBCs, and thrombocytes (platelets)
White blood cells
Agranulocytes – no granules present
Lymphocytes
Monocytes
Granulocytes – granules
Neutrophils
Eosinophils
Basophils
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3. White Blood Cells White blood cells Agranulocytes Granulocytes
Normally no granules present
Lymphocytes
Monocytes
If small granules present
Mononuclear leukocytes
Granulocytes
Granules
Neutrophils
Eosinophils
Basophils
a.k.a. polymorphonuclear leukocytes (PMNs)
Segmentation or lobulation of nucleus
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4. Blood Cells Constantly produced Finite life span so must be replaced
Life span differs by cell type and species
Begin in embryonic stages
Changes in processes as aging occurs
Hematopoietic activity
Prenatal
Liver, spleen, thymus, red bone marrow
Adult
Primarily red bone marrow
If stressed, may revert to production in liver and spleen
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5. Terms Erythropoiesis Leukopoiesis Thrombopoiesis
Production of erythrocytes
Leukopoiesis
Production of leukocytes
Thrombopoiesis
Production of thrombocytes
All involve different pathways and chemical messengers
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6. Pluripotent Hematopoietic Stem Cell (HSC)
All cells arise from this cell
Development determined by chemical messengers or cytokine
HSC
Common Myeloid Progenitor Cells Common Lymphoid Progenitor Cells
(CMP) (CLP)
Lymphocytes Erythrocytes
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7. Erythropoiesis Erythropoietin (EPO)
Cytokine responsible for production of RBCs
Produced by cells in kidneys in response to decrease in oxygen tension in blood
EPO circulates in the blood to the red bone marrow
Binds to receptors on erythroid precursor cells, causing them to divide and mature
Lesser amounts of APO = hepatocytes
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8. RBC Development EPO Erythroid precursor cells Rubriblasts
Pro-rubriblasts
Smaller than rubriblasts, slightly more dense basophilic cytoplasm, no visible nucleus
Rubricytes
Basophilic cytoplasm and clumping nucleus but changes as it matures
Metarubricytes
Smallest cells, condensed nucleus, and deep red cytoplasm
Cannot divide and hemoglobin formation completed
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9. RBC Development (cont.)
Reticulocytes
Immature RBCs
Lose ribosomal material
Small pieces remaining – punctate reticulocytes
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10. Thrombopoiesis Thrombopoietin Progenitor cells
Produced primarily in the liver
Progenitor cells
Megakaryoblast
Single nuclei – dark blue cytoplasm
Promegakaryocyte
Large cell – 2-4 nuclei
Megakaryocyte
Numerous nuclear lobes and reddish granules in cytoplasm
Cells are very large and shear apart in blood flow
Creating proplatelets
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11. Granulopoiesis Leukopoietin and numerous other cytokines
Cells are divided into a proliferation pool
Representing cell capable of mitosis
Includes
Myeloblasts
Large with round to oval nucleus, prominent nucleolus, pale gray–blue cytoplasm
Promyelocytes
Large, pale-staining, prominent reddish cytoplasmic granules with no obvious nuclei
Myelocytes
Smaller with a round nucleus – characteristics of mature cells appear
Band cells
Horseshoe-shaped nucleus with parallel sides
Segmented granulocytes
Nuclei with 2 or more lobes
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12. Monopoiesis Monoblasts Promonocytes Monocytes
Similar to myeloblasts but with a irregular-shaped nucleus
Promonocytes
Similar to myelocytes and metamyelocytes
Monocytes
May develop into macrophages with the right cytokines
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13. Lymphopoiesis Production of lymphocytes Develop T-lymphocytes
B-lymphocytes
Natural killer cells (NK)
Develop
CLP to lymphoblast and prolymphocyte stages
Differentiated by
B-lymphocyte precursor
T-lymphocyte or NK precursor
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14. Lymphopoiesis (cont.) T-lymphocytes
Requires certain cytokines and antibodies
Juvenile B-lymphocytes
Mature primarily in the bone marrow or specialized ileal Peyer patches in dogs, pigs, and ruminants or in the bursa of Fabricius in birds
T-lymphocytes
Mature in the thymus
NK cells
Mature in bone marrow but also thymus and other lymphoid tissues
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15. Terms -penia -philia Left-shift Leukemia Leukemoid response
Decreased number of cells
Neutropenia = decreased neutrophils
Pancytopenia = decrease of all blood cell types
-philia
Increased number of cells
Left-shift
Increased numbers of immature neutrophils
Leukemia
Neoplastic cells of blood or marrow
Leukemoid response
Mistaken for leukemia
Marked leukocytosis, usually inflammatory disease
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16. Summary Hematopoiesis Erythropoiesis Thrombopoiesis Leukopoiesis
Granulopoiesis
Monopoiesis
Lymphopoiesis
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