HEMATOPOIESIS
I-INTRODUCTION:
Blood represents approximately 0.7% of the body’s weight, or a volume varying between 4-5 liters in an adult of average size.
It is composed of mature cells called blood cells that bathe in a yellowish liquid called plasma.
There are 3 categories of blood elements:
-red blood cells which contain hemoglobin
-white blood cells which ensure the body’s defense against various attacks; there are 3 types: -granulocytes (eosinophils, basophils, neutrophils)
-Lymphocytes
-Monocytes
-platelets which play a crucial role in the blood clotting process.
Most of these elements have a lifespan, they must be renewed periodically.
*120 days for GR
*8-10 days for platelets
*a few days for GB
Hematopoiesis is the set of phenomena which ensure the continuous and regulated replacement of these blood cells from the hematopoietic stem cell.
II-LOCATION:
The seat varies according to the stages of life:
– Hematopoiesis is fetal during intrauterine life.
– takes place in the embryonic connective tissue until the 2nd month
-becomes hepatic and splenic from 2 to 6 months.
-it is medullary from the 4th month and coincides with the development of the bone sketches.
-after birth, normal hematopoiesis is located exclusively in the bone marrow.
-up to the age of 5 years all bones have hematopoietic activity.
Then this activity is gradually limited to the flat and short bones (sternum, ribs, iliac vertebrae)
III-THE HEMATOPOIESIS COMPARTMENTS:
– Hematopoiesis has 4 compartments:
*stem cells
*the progenitors
*precursors
*mature cells
1-PRIMITIVE STEM CELLS:
All the formed elements of blood are produced from the same indifferent cell called a multipotent stem cell or primitive stem cell.
These cells have two essential properties; the capacity for self-renewal and differentiation. Under the influence of stimulating factors, a multipotent stem cell will engage in the differentiation of a cell lineage.
2-PROGENITORS:
The first differentiation of a multipotent cell after its cycling is towards the lymphoid lineage or towards the myeloid lineage.
The lymphoid stem cell differentiates into two types of lymphocytes, T and B.
The myeloid stem cell is called CFU-GEMM.
Each progenitor name is defined by the association of the prefix CFU (Colony Forming Unit) followed by letter(s) which characterize the GEMM=Granular, Erythrocytic, Macrophagic, Megakaryocytic lineages
This cell will continue its differentiation program and give birth to even more committed progenitors.
CFU-GM: granulo-macrophagic…………..PNN and macrophages
CFU-MK megakaryocytic………………………….platelets
BFU-E (Burst FormingUnit) and CFU-E…………..red blood cells
3-THE PRECURSORS:
Hematopoietic precursors are the first morphologically identifiable cells of each lineage.
The precursor compartment is intended for cell multiplication and maturation.
They are located in the bone marrow and explored by myelogram and osteomedullary biopsy.
4-MATURE CELLS:
These are the terminal, mature and functional cells which pass into the peripheral blood: polymorphonuclear neutrophils, eosinophils, basophils, lymphocytes, monocytes, red blood cells and platelets.
For most cells, blood only represents a passageway between their place of production (bone marrow) and the place of their functions (tissues).
IV-REGULATION:
Bone marrow stem cells are the essential basis for effective hematopoiesis. Three elements play an important role in achieving correct and regulated hematopoiesis: the bone marrow microenvironment, certain vitamins and trace elements, and growth factors.
1-the medullary microenvironment:
It participates in the general organization of the marrow. It gives stem cells the satisfactory anatomical and intercellular conditions to ensure hematopoiesis.
The extracellular matrix is composed of various fibrous proteins, glycoproteins and proteoglycans
2-vitamins and trace elements:
Essential for hematopoiesis: vitamin B9, B12 and iron.
3-growth factors:
Also called cytokines; several types of these factors are distinguished according to their place of action during hematopoiesis:
Erythropoietin: erythroid lineage
-thrombopoietin, IL6: megakaryocytic lineage
-IL4: basophilic granular lineage
IL5: eosinophilic granular lineage
G-CSF: neutrophil granular lineage
M-CSF: monocytic lineage
V-CONCLUSION:
Hematopoiesis is a complicated and clearly organized and regulated process ensuring the continuous replacement of the formed elements of the blood.
HEMATOPOIESIS PROCESS.
HEMATOPOIESIS
HEMATOPOIESIS
HEMATOPOIESIS
FACULTY OF MEDICINE -ANNABA
HEMATOLOGY MODULE
4th YEAR
DENTAL SURGERY
DR.SMAILI
HEMATIMETRY
I-DEFINITION:
Hematology is the set of quantitative and qualitative measurements of the formed elements of the blood. It is carried out from a blood sample taken by venipuncture and collected in a tube containing a dry anticoagulant of the EDTA type.
A blood smear will be taken from the tube, or better from blood that has not been in contact with the anticoagulant for precise identification of the cells and their abnormalities.
II-QUANTITATIVE STUDY
A-RED LINE
Red blood cell counts, hemoglobin and hematocrit vary depending on age, gender
1-RED BLOOD CELL RATE
Adult female: 4-5 million cells/mm3
Adult male: 4.5-5.5 million cells/mm3
2- HEMOGLOBIN
Newborn: 14-23 g/dL
Children 6-12 years: 11.1-14.7g/dl
Adult male: 14-18 g/dl
Adult female: 12-16g/dlg/L
Pregnant women (from the second trimester of pregnancy): 10.5 g/dL
3-HEMATOCRITE:
It is the volume of circulated blood occupied by red blood cells.
Adult women: 38-47%
Adult male: 40-54%
-polyglobulia: GR, HB, Hte levels increased compared to normal values
-anemia: GR, HB, Hte levels reduced compared to normal values
4- ERYTHROCYTE INDICES
A* MEAN CLOTTED VOLUME (MCV)
Measured by automata, it can be calculated by the ratio between the hematocrit and the number of red blood cells.
VGM = hematocrit x10
GR
The normal value is 85 to 100 fl or μ3 (cubic micron) regardless of age
In practice, the following definitions are generally used:
● Microcytosis = VGM < 85fl
● Macrocytosis = MCV > 100 fl
B*AVERAGE CORPUSCULAR HEMOGLOBIN CONCENTRATION
(CCMH)
The Mean Corpuscular Hemoglobin Concentration (MCHC) corresponds to the average hemoglobin concentration per red blood cell (hemoglobin divided by hematocrit).
CCMH = HB X100
HK
Normal values are between 32 and 36 g/dL or % regardless of age and allow us to define:
● CCMH < 32: Hypochromia
● 36 < CCMH > 32: Normochromy
A CCMH > 36 first suggests a blood count artifice most often linked to the presence of cold agglutinin.
C*AVERAGE HEMOGLOBIN CONTENT (TGMH)
The Mean Red Blood Cell Hemoglobin Content (MRHC) corresponds to the average weight of hemoglobin contained in a red blood cell (Hb divided by the number of red blood cells).
TGMH = HBx10
GR
Normal values are 27 to 32 pg per cell.
5-RETICULOCYTE RATE
Reticulocytes are the precursors of red blood cells that have not yet lost their RNA, whose lifespan is 24-48 hours.
Rate: 25000-100000 elements/mm3 or: 0.5-2% outside of anemia
This value evaluates the bone marrow capacity for producing red blood cells.
*TR˂120000 cells/mm3 aregenerative anemia (central)
*TR˃120000 cells/mm3 regenerative anemia (peripheral)
B-WHITE LINE:
The white blood cell count varies depending on age:
● Birth: 10000 to 26000 e/mm3
● Adult: 4000 to 10000 e/mm3
Leukocytes (in adults):
> 10000 e/mm3 = hyperleukocytosis
< 4000 e/mm3 = leukopenia
ABSOLUTE COUNT OF LEUKOCYTES
Poly. neutrophils 40-70% or 1600 – 7000 elements/mm3
Poly. eosinophils 00-07% or 0 – 700 elements/mm3
Poly. basophils 00-03% or 0 – 300 elements/mm3
Lymphocytes 20-40% or 800 – 4000 elements/mm3
Monocytes 3-7% or 120 – 700 elements/mm3
C- Platelets (regardless of age and gender):
● 150000 – 450000 e/mm3 = Normal
● < 150000 e/mm3 = Thrombocytopenia
● > 450,000e/mm3 = Hyperplateletosis (Thrombocytosis)
Any thrombocytopenia without signs of hemorrhage should lead to a search for false thrombocytopenia with EDTA (by agglutination of platelets); by a blood smear from the finger or a sample from a citrate tube.
III-QUALITATIVE STUDY
This is the analysis of a blood smear stained with MGG under an optical microscope.
GR:
In its normal state, the GR is spherical in appearance, pale in the center, orange-red in color, and 7-8 micrometers in size.
1-size anomalies: anisocytosis
-macrocytosis: large RBCs.
-microcytosis: small RBCs
2-form abnormality: poikilocytosis
Sickle cell, ovalocyte, spherocyte, schistocyte, elliptocyte, dacryocyte, acanthocyte .
3-color anomaly: anisochromia
Hypochromia, target cell, annulocyte, polychromatophilia
WHITE BLOOD CELLS
Establish the leukocyte balance as a percentage and then convert it into absolute figures. Allows abnormal cells to be highlighted: leukoblasts, myelemia, erythroblasts, etc.
PLATELETS
The finger blood smear allows a semi-quantitative evaluation of the plq
CYTOPENIA
* if two lines are affected: bicytopenia
* if three lines are affected: pancytopenia
The mechanism of cytopenia can be central or peripheral.
HEMATOPOIESIS
IV-C0NCLUSION
The blood count is a highly requested test in current practice; the interpretation of which guides the diagnostic and therapeutic approach.
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