1.
HAEMOPOIESIS
•Development of blood cells
•Erythropoiesis – RBCs
(Process of formation and maturation of RBCs )
•Leucopoesis – WBCs
•Megakaryopoesis- Platelets

2.
Sites of haemopoiesis
1.Intrauterine life : 3 stages
A) Mesoblastic
stage :
up to 3 week of foetal life Mesoderm of the yolk
sac
B) Hepatic stage : From 3 rd week –to 6m Liver, spleen
C) Myeloid stage : From 6 mths – full term Red Bone Marrow
2) In children : Upto 6yrs marrow of all bones
3) In Adults :
Upto 20yrs long bones ,vertebrae,
skull ,Ribs, Sternum, ilia
After 20yrs: Upper ends of long
bones, vertebrae, ribs,
sternum, ilia

3.
Bone Marrow
The bone marrow - one of the most active organs
Active BM: red marrow- cells at different stages of
development…
Inactive BM infiltrated with fat: yellow marrow
• BM is aspirated from iliac bone/sternum….properly
stained…examined under microscope..
• Indications: anemia..leukemia, lymphoma, pancytopenia

4.
BFU-E
HEMOPOESIS

5.
Bone Marrow….
• 75% of the cells in the marrow belong to the myeloid
series ( for WBC & Platelets)
• Only 25% - red cells.
• Normal myeloid- erythroid ratio is 3:1
• In circulation RBC count is 500 times more than WBC
count…because of longer life span of RBCs…

6.
PPSC → COMMITTED STEM CELLS
BFU -E
↓
CFU – E
↓
PROERYTHROBLAST
↓
EARLY NORMOBLAST
↓
INTERMEDIATE NORMOBLAST
↓
LATE NORMOBLAST
↓
RETICULOCYTE
↓
ERYTHROCYTE
Stages Of Erythropoesis

7.
Proerythroblast / Pronormoblast
• First identifiable cell of erythroid series
• Cell size – 15- 20 micrometer
• Nucleus occupies 3/4TH of cell volume with multiple nucleoli
• Chromatin threads present
• Cytoplasm – basophilic (high concentration of polyribosomes)
• Mitosis – present
• Hb – absent

8.
Early Normoblast /Basophilic Normoblast
• 14 – 16 micrometer
• Nucleus size – decrease –nucleoli absent
• Chromatin condensation present
• Cytoplasm – basophilic
• Mitosis – present
• Hb – absent

9.
Intermediate Normoblast
(Polychromatophilic normoblast )
• Cell size – decrease – 10 – 14 micrometer
• Nucleus size – decrease
• Hb – starts appearing
• Cytoplasm –Polychromatophilic
• – bluish and pinkish (basophilic RNA & acidophilic Hb)
• Mitosis – present

10.
Late Normoblast/Orthochromatic Normoblast
• 8 – 10 micrometer
• Eccentric cart wheel nucleus
• Pyknotic degeneration- clumping of the chromosomes,
shrinking of the nucleus.
• Cytoplasm - reddish (Acidophilic)
• No mitosis
• Hb – present
• Nucleus is extruded out later

11.
Reticulocyte
• Cell size decrease 7 – 8 micrometer
• Nucleus absent
• RNA appears as a reticulum on Supravital Staining (with
Brilliant Cresyl Blue)
• Hb increased
• Reticulocyte spends 1-2 days in bone marrow and 1-2 days in
the peripheral blood..spleen ..matures into biconcave RBC
• Mitochondria, ribosomes etc are lost when converted to
RBCs…so RBC cannot synthesize proteins..

12.
Reticulocyte…..
•Normal count:
In infants: 2-6% of RBC count
Adult - 0.5 to 1% of RBC count
Reticulocytosis
• Physiological – at birth, infants ,high altitude
• Pathological – hemolytic anemia
• Reticulocytopenia – Aplastic anemia

13.
Erythrocyte
• Cell size – 7.2- 7.5 micrometer
• Absence of RNA material, no organelles
• One Pronormoblast give rise to at least 8-10 RBCs
• 2 million RBCs produced each sec
• Average duration of Erythropoiesis: 7 to 9 days
Proerythroblast to reticulocyte takes 5 to 7 days
Maturation of reticulocyte to RBC takes 2 days..
• Life span = 120days

14.
Factors Affecting Erythropoesis
General factors
- Hypoxia  Erythropoietin
- Growth inducers
- Hormones
Maturation factors
- Iron, Vitamin B 12,Folic acid
Factors necessary for hemoglobin production
- Vitamin C Helps in iron absorption (Fe3+  Fe2+)
- Proteins  Amino Acids for globin synthesis
- Iron, copper, cobalt & nickel Heme synthesis

15.
1.ERYTHROPOETIN ( EPO)
• Glycoprotein.
Formation
• 85% formed in endothelial cells of the
peritubular capillaries of the renal
tubules.
• 15% formed in liver
Breakdown
 In liver. Half life is 5 hours
PTC

16.
Renal tissue hypoxia

tissue levels of Hypoxia-inducible Factor-1 (HIF-1),

HIF-1 binds to a hypoxia response element in the
Erythropoietin gene,

Transcription of messenger RNA and,

increased Erythropoietin synthesis

17.
Stimuli increasing EPO
Hypoxia is the potent stimulus
High altitude
Anemia
Chronic lung or heart diseases
Catecholamines
Androgens
•Decreased by
Estrogen

18.
Functions of EPO
Erythropoietin increases RBC production -
• Stimulates stem cells towards erythroid series
• Promotes pronormoblast production from progenitor cells
• Enhances mitosis
• Accelerates Hb synthesis
• Promotes the early release of reticulocytes.
Applied – EPO injections in treatment of anemia in renal
failure

19.
2.Growth inducers/ Differentiation inducers
• Interleukin 1, 3, 5 (IL-3 is a growth inducer for all cell lines )
Acts on stem cells to convert them to progenitor cells
• Colony stimulating factors – produced from T cells,
endothelial cells, fibroblasts stimulates production of
committed stem cells .
3. Hormones
•Androgens  & Estrogen  Erythropoesis
•. Thyroxine , GH, Cortisol –stimulates Erythropoesis

20.
Maturation factors
Role of iron ,folic acid & vitamin B12.
• Iron- needed for Hb synthesis
• Folic acid & Vit B12- required for the synthesis of DNA and
maturation of nucleus and cell.
• Milk ,meat ,liver ,Green leafy vegetables
 If deficiency occurs… failure of maturation of nucleus.
 There occurs reduction in the cell division.
Cells remain large (megaloblasts) and become more
fragile.
• Intrinsic factor – needed for Vit B12 absorption

21.
Other dietary factors
•Vitamin C Helps in iron absorption (Fe3+ 
Fe2+)
•Proteins  Amino Acids for globin synthesis
•Copper, cobalt & nickel.  Heme synthesis
(Copper- incorporation of Fe into Porphyrin Ring )