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Haematopoiesis - Overview (view source)
Revision as of 18:23, 14 February 2022
, 18:23, 14 February 2022→Introduction
[[Image:LH_Variety_blood_cells_Histology.jpg|right|thumb|210px|<p>'''Blood cells'''</p><sup>©RVC 2008</sup>]]
Examination of blood from animals can provide valuable information regarding the health status of an animal. Rarely is haematology examined in isolation. Most often haematology and a
biochemistry profile are considered in conjunction, to maximise interpretive data. For example a chronic nonregenerative or poorly regenerative anaemia is often associated with chronic kidney disease. (NW)[[Image:LH_Variety_blood_cells_Histology.jpg|right|thumb|210px|<p>'''Blood cells'''</p><sup>©RVC 2008</sup>]]
==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><sup>©RVC 2008</sup>]]
[[Image:LH_Avian_Variety_blood_cells_Histology.jpg|right|thumb|210px<p>'''Avian Blood cells'''</p><sup>©RVC 2008</sup>]]
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 B cells and T cells ([[Leukopoiesis#Lymphopoiesis|Lymphopoiesis]])
* Formation of B cells and T cells ([[Leukopoiesis#Lymphopoiesis|Lymphopoiesis]])
== Hematopoyesis and Distribution of Cells in the Body (NW) ==
Erythrocytes, platelets and granulocytes (neutrophils, eosinophils and basophils) are derived from pluripotential stem cells. These give rise to multipotential colony-forming unit progenitors for granulocytes, erythrocytes, monocytes/macrophages and megakaryocytes. Under the influence of interleukins and colony-stimulating factors, committed stem cells develop into differentiated blood cells (erythrocytes, neutrophils, eosinophils, basophils, monocytes and platelets). Neutrophils and monocytes develop from the same colony-forming unit. Although the bone marrow produces some lymphocytes most are derived from the peripheral lymphoid tissue.
The bone marrow also contains a reserve of mature cells, which can be released into the circulation. Thus, changes in the blood are affected by the reserve capacity of the bone marrow and the life span of cells in the circulation (canine erythrocytes 120 days, platelets 10 days, granulocytes 8 hours).
Haematopoiesis may occur in other organs particularly the spleen, less frequently the liver and even peripheral lymph nodes, if there is a marked increase in demand for cells. With increased tissue demands, mature reserves are depleted and immature cells are released into the circulation.
[[File:NWL 2016 Labfacts inners A4 PRESS optimize(40).jpg|thumb|Bone Marrow Citology and Histology]]
[[File:NWL 2016 Labfacts inners A4 PRESS optimize(90).jpg|thumb|Bone Marrow Histology]]
==Foetal Haematopoiesis==
==Foetal Haematopoiesis==