Hematopoiesis: Hemopoiesis
Greek: haima = blood, poiesis=making
Hematopoietic Systems: Bone Marrow, Liver, Spleen, Lymph nodes, Thymus
3 THEORIES IN HEMATOPOIESIS
Monophyletic Theory FROM: a single progenitor stem cell called PLURIPOTENT HEMATOPOIETIC
STEM CELL
Polyphyletic Theory DUALISTIC THEORY 2/3 cell origin:
1. Lymphoblast= lymphocytes
2. Myeloblast= granulocyte, monocyte,
megakaryocyte
3. Pronormoblast= erythrocytes
TRIALISTIC THEORY -same to dualistic but:
-by Schilling Reticuloendothelial cells lining the sinusoid of the
spleen & liver= monocytes
Complete Theory Stem cell for EACH several cell series
-proposed by Sabin et
al.
TYPES OF HEMATOPOIESIS
PRIMITIVE DEFINITIVE
a. Transient, continues to week 8 a. Persists throughout the natal life
b. It arises in the blood island of the b. It arises slightly later than the primitive
extraembryonic sac hematopoiesis and begins in the
c. Blood cells are mainly erythrocytes, splanchnopleura/ aorta-gonad-
nucleated. Restricted to maturing mesonephros (AGM) of the developing
primitive erythroid, macrophage, and embryo
megakaryocytes c. Consists of the erythroid, megakaryocyte,
d. Reduced erythropoietin requirements and multiple myeloid, lymphoid, lineages.
Erythrocytes are anucleated.
d. Requires erythropoietin for survival
during differentiation
e. They rapidly seed the fetal liver, which is
the major site of hemopoiesis in the
midgestational period The spleen also
participates in this process at this period.
3 STAGES OF HEMATOPOIESIS
Chief Cite Starts at Cells formed
Mesoblastic/ blood 19thday of Erythroblast/ ERYTHROPOIESIS: RBC production, granulopoiesis,
gestation pronormoblasts thrombopoiesis
Megaloblastic island of
(immature RBCs) Formed 4 globin chains
Stage the yolk blood islands Embryonic
sac active for 8- Hemoglobin
12 weeks Gower I 2 Zeta & 2 Epsilon chains
Gower II 2 Alpha & 2 Epsilon chains
Greek: haima = blood, poiesis=making
Hematopoietic Systems: Bone Marrow, Liver, Spleen, Lymph nodes, Thymus
3 THEORIES IN HEMATOPOIESIS
Monophyletic Theory FROM: a single progenitor stem cell called PLURIPOTENT HEMATOPOIETIC
STEM CELL
Polyphyletic Theory DUALISTIC THEORY 2/3 cell origin:
1. Lymphoblast= lymphocytes
2. Myeloblast= granulocyte, monocyte,
megakaryocyte
3. Pronormoblast= erythrocytes
TRIALISTIC THEORY -same to dualistic but:
-by Schilling Reticuloendothelial cells lining the sinusoid of the
spleen & liver= monocytes
Complete Theory Stem cell for EACH several cell series
-proposed by Sabin et
al.
TYPES OF HEMATOPOIESIS
PRIMITIVE DEFINITIVE
a. Transient, continues to week 8 a. Persists throughout the natal life
b. It arises in the blood island of the b. It arises slightly later than the primitive
extraembryonic sac hematopoiesis and begins in the
c. Blood cells are mainly erythrocytes, splanchnopleura/ aorta-gonad-
nucleated. Restricted to maturing mesonephros (AGM) of the developing
primitive erythroid, macrophage, and embryo
megakaryocytes c. Consists of the erythroid, megakaryocyte,
d. Reduced erythropoietin requirements and multiple myeloid, lymphoid, lineages.
Erythrocytes are anucleated.
d. Requires erythropoietin for survival
during differentiation
e. They rapidly seed the fetal liver, which is
the major site of hemopoiesis in the
midgestational period The spleen also
participates in this process at this period.
3 STAGES OF HEMATOPOIESIS
Chief Cite Starts at Cells formed
Mesoblastic/ blood 19thday of Erythroblast/ ERYTHROPOIESIS: RBC production, granulopoiesis,
gestation pronormoblasts thrombopoiesis
Megaloblastic island of
(immature RBCs) Formed 4 globin chains
Stage the yolk blood islands Embryonic
sac active for 8- Hemoglobin
12 weeks Gower I 2 Zeta & 2 Epsilon chains
Gower II 2 Alpha & 2 Epsilon chains
