Changes

[[Image:LH_Variety_blood_cells_Histology.jpg|right|thumb|210px|<p>'''Blood cells'''</p>^{©RVC 2008}]]

[[Image:LH_Variety_blood_cells_Histology.jpg|right|thumb|210px|<p>'''Blood cells'''</p>^{©RVC 2008}]]

==Introduction==

==Introduction==

Haematopoiesis is also known as haemopoiesis or hemopoiesis and describes the process of blood cell formation. All blood cells are derived from the initial pluripotent stem cell (PPSC) which gives rise to colony forming units (CFUs). These CFUs further differentiate to give rise to their final stage of development where they become the various forms of blood cells or those cells which migrate from the circulation into tissues, such as mast cells and macrophages.

Haematopoiesis is also known as haemopoiesis or hemopoiesis and describes the process of blood cell formation. All blood cells are derived from the initial pluripotent stem cell (PPSC) which gives rise to colony forming units (CFUs). These CFUs further differentiate to give rise to their final stage of development where they become the various forms of blood cells or those cells which migrate from the circulation into tissues, such as mast cells and macrophages.

==Development==

==Development==

[[Image:LH_Avian_Variety_blood_cells_Histology.jpg|right|thumb|210px<p>'''Avian Blood cells'''</p>^{©RVC 2008}]]

[[Image:LH_Avian_Variety_blood_cells_Histology.jpg|right|thumb|210px<p>'''Avian Blood cells'''</p>^{©RVC 2008}]]

PPSC’s initially divide and differentiate into multipotential haematopoietic stem cells of one of two lineages: myeloid progenitors (granulocytes, erythroblasts, [[Macrophages|macrophages]] and megakaryocytes) or lymphoid progenitors (B lymphocytes, T lymphocytes and NK cells).  

PPSC’s initially divide and differentiate into multipotential haematopoietic stem cells of one of two lineages: myeloid progenitors (granulocytes, erythroblasts, [[Macrophages|macrophages]] and megakaryocytes) or lymphoid progenitors (B lymphocytes, T lymphocytes and NK cells).

The development of blood cells from the haematopoietic stem cell into the final mature cell is categorised into:

The development of blood cells from the haematopoietic stem cell into the final mature cell is categorised into:  

* The formation of red blood cells ([[Erythropoiesis|Erythropoiesis]])

* The formation of red blood cells ([[Erythropoiesis|Erythropoiesis]])

* The formation of white blood cells ([[Leukopoiesis|Leukopoiesis]])

* The formation of white blood cells ([[Leukopoiesis|Leukopoiesis]])

* Formation of neutrophils, eosinophils and basophils ([[Leukopoiesis#Granulopoiesis|Granulopoiesis]])

* Formation of neutrophils, eosinophils and basophils ([[Leukopoiesis#Granulopoiesis|Granulopoiesis]])

* Formation of B cells and T cells ([[Leukopoiesis#Lymphopoiesis|Lymphopoiesis]])

* Formation of B cells and T cells ([[Leukopoiesis#Lymphopoiesis|Lymphopoiesis]])

 

==Foetal Haematopoiesis==

==Foetal Haematopoeisis==

====Yolk Sac Phase====

====Yolk Sac Phase====

<p>Blood islands from the mesoderm  form in the yolk sac early in gestation. They provide primitive erythrocytes to support the developing embryo. These blood islands also give rise to the haematopoietic stem cells.</p>

<p>Blood islands from the mesoderm  form in the yolk sac early in gestation. They provide primitive erythrocytes to support the developing embryo. These blood islands also give rise to the haematopoietic stem cells.</p>

|colspan="3" style="background-color:#e6e6fa"|'''[[T cells|T cell]]''', '''[[B cells|B cell]]''' & '''[[Natural Killer cells|NK cell]]'''

|colspan="3" style="background-color:#e6e6fa"|'''[[T cells|T cell]]''', '''[[B cells|B cell]]''' & '''[[Natural Killer cells|NK cell]]'''

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[[Category:Haematopoiesis|A]]

[[Category:Haematopoiesis|A]]