HEMOPOIESIS AND STEM CELLS
- Development of major blood cells
- The bone marrow is the factory for blood cells
- Stem cells in the bone marrow are pluripotent
- In the early embryo, blood cells arise in the yolk sac mesoderm
- In the second trimester hemopoiesis occurs primarily in the
developing liver with the spleen playing a minor role
- Skeletal elements begin to ossify, and the bone marrow develops
so in the third trimester marrow of specific bones become the
major hemopoietic organ
, - The origin and maturation of these cells are termed, respectively:
erythropoiesis, granulopoiesis, monocytopoiesis, and
thrombocytopoiesis
- Lymphopoiesis or lymphocyte development occurs in the bone
marrow and in the lymphoid organs to which precursor cells
STEM CELLS, GROWTH FACTORS & DIFFERENTIATION
- Capable of self-renewal
, HEMOPOIETIC STEM CELLS
- All blood cells arise from a single type of hemopoietic stem cell
- These pluripotent stem cells are rare, proliferate slowly and give
rise to two major lineages of progenitor cells one for lymphocytes
and another for myeloid cells
- Myeloid cells include granulocytes, monocytes, erythrocytes and
megakaryocytes
- The lymphoid progenitor cells migrate from bone marrow to the
thymus or lymph nodes, spleen or other lymphoid tissue where
they proliferate and differentiate
PROGENITOR & PRECURSOR CELLS
- The progenitor cells for blood cells are often called COLONY –
FORMING UNITS (CFUs)
- Because they give rise to colonies of only one cell type when
cultured in vitro or injected into a spleen
- There are four major types of progenitor cells:
1. Erythroid lineage of erythrocytes
2. Thrombocytic lineage of megakaryocytes for platelet
formation
3. Granulocyte – monocyte lineage of all three granulocytes and
monocytes
- Development of major blood cells
- The bone marrow is the factory for blood cells
- Stem cells in the bone marrow are pluripotent
- In the early embryo, blood cells arise in the yolk sac mesoderm
- In the second trimester hemopoiesis occurs primarily in the
developing liver with the spleen playing a minor role
- Skeletal elements begin to ossify, and the bone marrow develops
so in the third trimester marrow of specific bones become the
major hemopoietic organ
, - The origin and maturation of these cells are termed, respectively:
erythropoiesis, granulopoiesis, monocytopoiesis, and
thrombocytopoiesis
- Lymphopoiesis or lymphocyte development occurs in the bone
marrow and in the lymphoid organs to which precursor cells
STEM CELLS, GROWTH FACTORS & DIFFERENTIATION
- Capable of self-renewal
, HEMOPOIETIC STEM CELLS
- All blood cells arise from a single type of hemopoietic stem cell
- These pluripotent stem cells are rare, proliferate slowly and give
rise to two major lineages of progenitor cells one for lymphocytes
and another for myeloid cells
- Myeloid cells include granulocytes, monocytes, erythrocytes and
megakaryocytes
- The lymphoid progenitor cells migrate from bone marrow to the
thymus or lymph nodes, spleen or other lymphoid tissue where
they proliferate and differentiate
PROGENITOR & PRECURSOR CELLS
- The progenitor cells for blood cells are often called COLONY –
FORMING UNITS (CFUs)
- Because they give rise to colonies of only one cell type when
cultured in vitro or injected into a spleen
- There are four major types of progenitor cells:
1. Erythroid lineage of erythrocytes
2. Thrombocytic lineage of megakaryocytes for platelet
formation
3. Granulocyte – monocyte lineage of all three granulocytes and
monocytes
