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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..