By-SUMIT KUMAR SINGH

1. Erythropoiesis
SUMIT KUMAR
KMC
MANGALORE

2. Scheme
• Origin
• Definition
• Sites of erythropoiesis
• Stages of erythropoiesis
• Changes during erythropoiesis

3. Haemopoiesis
• Hemo: Blood cells
• Poiesis: “The development and production of”
• The word Hemopoiesis refers to production
and development of all blood cells:
• Erythropoiesis – development of RBC
• Leucopoiesis – development of WBC
• Thrombopoiesis – development of platelets

4. Origin
Ref: Google

5. DEFINITION
Process which involves origin, development and
maturation of erythrocytes

6. Sites
• In fetal life
• In new born babies
• In children
• In adult

7. Sites Contd…
7
In fetal life
Mesoblastic stage Myeloid stageHepatic stage

8. Sites Contd…
Mesoblastic stage
• 3rd week  3rd month(Intrauterine life)
• Mesoderm of yolk sac
• Intravascular erythropoeisis
8

9. Sites Contd…
 Hepatic stage
- 3rd to 5th month
- Liver, Spleen and Lymph nodes
 Myeloid stage
- 5th month onwards
- Red bone marrow

11. Sites of erythropoiesis
In children
• All bones with red bone
marrow
In adults (after 20yrs)
• Ends of long bones like
Femur, Humerus ,Skull,
Vertbrae ,Ribs, Sternum,
pelvis
Ref: Google

12. Stages of erythropoiesis
• Stem cells
 Extensive proliferative capacity
 Ability to give rise to new stem cells (Self Renewal)
 Ability to differentiate into any blood cell lines
(Pluripotency)
• Hematopoietic stem cells (HSCs)
 Bone marrow cells capable of producing all types of
blood cells
 Differentiate into one or another type of committed
stem cells (progenitor cells)

13. Proerythroblast
• 15-20 microns
• Nucleus with multiple
nucleoli
• Basophilic cytoplasm
• No hemoglobin
• Mitosis present
Ref: Google

14. Basophilic/ early normoblast
• Slight reduction in
size 12-18μm
• Large nucleus,
• nucleoli not seen
• Basophilic cytoplasm
• Active mitosis
• Hemoglobin appears

15. Polychromatophilic / intermediate
normoblast
• 10-15μm size
• Polychromatic
• Nucleus condenses
• Coarse chromatin
• Hemoglobin starts appearing
• Reduced mitoses

16. Orthochromatic normoblast
• 7-10μm
• Acidophilic erythroblast
which is the last precursor
with a nucleus
• Nucleus is compact and
situated near membrane
• Pyknotic nucleus is extruded
• Cytoplasm is like mature red
Cell, reflecting a high Hemoglobin
content
• Mitosis absent

17. Reticulocyte
• Reticular nuclear fragments
• Nucleus extruded
• Slightly larger than RBCs

18. Reticulocyte
• Young erythrocytes
• Makes up 0.5-2% of all erythrocytes
• Vital staining required
to make this visible
• Reticulocytosis seen
following hemolysis,
acute blood loss, in
severe anemia

19. Reticulocyte
• No nucleus
• Larger than mature RBC
• In severe anemia, many of these are released
into the blood
• Prematurely reticulocyte response
• Normally 1% of circulating blood are
reticulocytes

20. Reticulocyte response
• It indicates a favorable response to treatment
• When therapy begins new red cells are
formed and released rapidly into circulation
before cells fully matured,therefore many
reticulocytes also release with young red cells
this results increase in reticulocyte called
reticulocyte response

21. Mature erythrocyte
• Reddish, circular, biconcave cells
• 7-8 μ
• No visible internal structure
• High Hemoglobin content
• Biconcave shape

23. Duration of erythropoiesis
• Differentiation
phase: from
pronormoblast to
reticulocyte phase - 5
days
• Maturation phase:
from reticulocyte to
RBC- 2 days

24. Summary:
Changes during erythropoiesis
• Decrease in cell size (from diameter of 20-7.2μ)
• Loss of mitotic activity (later part of intermediate
normoblast)
• Hemoglobin first starts appearing (intermediate
normoblast)
• Change of cell shape (from globular to biconcave)
• Disappearance of nucleus, mitochondria, RNA, etc
• Change of staining (basophilic – eosinophilic)

26. Stages of erythropoiesis
Ref:Guyton