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MLAB 1415- Hematology
Keri Brophy-Martinez
Chapter 4 :
Hematopoietic
Organs
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Hematopoiesis: overview
Medullary Origin of blood cells and sequential sites of normal
blood production within the bone marrow
Extramedullary Blood cell production in hematopoietic tissue
other than bone marrowLiver
Spleen
Compensatory mechanism to provide blood cellsin times of need
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Ontogeny (origin) of Hematopoiesis
From third to sixth month,
hematopoiesis occurs in
kidney, thymus, spleen and lymph
nodes
Other emerging cells About three months of life, see platelets
About five months of life, see leukocytes
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Ontogeny (origin) of Hematopoiesis
Around seventhmonth of fetal life,hematopoiesis shiftsto bone marrow
Fetal marrow fills withRBCs
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Ontogeny (origin) of Hematopoiesis
At birth, liverand spleen stop
hematopoietic
activity.
Bone marrow
now becomes
active site ofhematopoiesis
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Ontogeny (origin) of Hematopoiesis
Children up to teen years,has hematopoiesis in allbones
Hematopoiesis gradually
decreases in shafts of longbones.
Around age 18-20hematopoiesis shifts toproduction in sternum,
ribs, pelvis, vertebrae, andskull.
After age 40, less area inthese sites available for
hematopoiesis.
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Storage Pools
Granulocytes and
platelets also exist in
two pools
Circulating Marginal
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Bone Derived Cells
Non-hematopoietic cells involved with bone
turnover closely linked with hematopoiesis Osteoblasts
Responsible for the formation, calcification and maintenance of the
bone structure
Large irregularly shaped cells in the bone marrow that may be confused
with plasmacytes or malignant cells
Osteoclasts
Responsible for absorption of bone
Assist in degradation of bone
Giant multinucleated, irregularly shaped phagocytic
cells in the bone marrow that may be confused with
megakaryocytes
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Bone Derived Cells
Osteoblast Osteoclast
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References
Harmening, D. M. (2009). Clinical
Hematology and Fundamentals of
hemostasis (5th ed.). Philadelphia, PA:
F.A. Davis Company.
McKenzie, S. B. (2010). Clinical
Laboratory Hematology(2nd ed.). Upper
Saddle River, NJ: Pearson Education, Inc..
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