Rabu, 18 Maret 2009

Fisiologi Ternak, Hemopoiesis, hemopoietic

Anatomy and Physiology of Hemopoiesis

The Bare Essentials

(what you really need to know)

1. All blood cells originate from pluripotent stem cells which reside in the bone marrow and circulate in the blood

2. The pluripotent stem cell differentiates (commits) into two lineages in the bone marrow: the myeloid lineage and the lymphoid lineage

3. The myeloid lineage gives rise to all myeloid cells – erythrocytes, granulocytes (neutrophils, eosinophils, basophils), monocytes and platelets

4. The lymphoid stem cell is generated in the bone marrow: thereafter, development of T and B-cells involves the marrow, thymus, and peripheral lymphoid organs

5. Hematological neoplasms may affect the pluripotent stem cell or any of its committed progeny

Stem cells may be harvested from the blood or marrow and used to treat patients

1. Stem Cells

1. Stem Cells must exist

Adult humans produce about 2 x 1011 erythrocytes (lifespan 100 days), 2 x 1011 neutrophils (lifespan 6 h in circulation) and 2 x 1011 platelets (lifespan 7 days) from the bone marrow daily. Mature blood cells are incapable of division, so this output must arise from precursor cells, otherwise known as progenitor or stem cells. Stem cells have not been visually identified. Their existence is a logical necessity, and can be inferred from various functional assay systems.

Cell type

Approximate lifespan

Production rate cells/day

Production rate cells/sec

Production rate Kg/year

Red Cells

100 days

2 x 1011

2.3 million



t½ 6 hours

3 x 1010




7 days

1 x 1011

1.2 million



t½ 10 days

1 x 1010



Annual total

26.5 Kg


A ‘stem cell’ is a cell capable of both self-renewal and differentiation.

A ‘pluripotent’ hemopoietic stem cell can give rise to cells of all hemopoietic lineages i.e. myeloid cells and lymphoid cells.

A ‘committed’ stem cell has a capability restricted to one or more lineages.

‘Myeloid’ cells are erythrocytes, granulocytes (neutrophils, eosinophils, basophils), megakaryocytes, and macrophages.

‘Lymphoid’ cells are T and B lymphocytes and NK cells.

Stem Cell Hierarchy

Small numbers of pluripotent stem cells give rise to larger numbers of stem cells with ever-increasing lineage commitment

Full Teks Link Person Eko Budi Santoso Proter 2005 Fapet UB

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