For MBBS students

1. RED BLOOD CELL- II
ERYTHROPOIESIS
STAGES / FACTORS REGULATING
Dr. Elizabeth J
Prof & HOD,
AIMS &RC,
Bangalore
04/09/14

2. Scheme
 Definition
 Theories of erythropoiesis
 Sites of erythropoiesis
 Stages of erythropoiesis
 Description of blast cells
 Reticulocyte
 Mature Red Cell
 Factors affecting Erythropoiesis
 Erythropoietin
 Absorption of Vitamin B12

3. DEFINITION
DEVELOPMENT
MULTIPLICATION
MATURATION
DIFFERENTIATION

4. “Theories that address the process of
commitment of stem cell progeny”
STOCHASTIC THEORY
 HAEMPOIETIC INDUCTIVE
MICROENVIRONMENT
 HUMORAL FACTORS

5. Site of Erythropoiesis
3 stages of erythropoiesis during
intrauterine life
o mesoblastic (1st 3 months)
o hepatic (after 3 months)
o myeloid (3rd trimester)

7. PHSC Pluripotent Hemopoietic stem cell
BFU-E Burst Forming Unit Erythrocyte
CFU-E Colony Forming Unit Erythrocyte
PROERYTHROBLAST
BASOPHILIC ERYTHROBLAST
POLYCHROMATOPHILIC ERYTHROBLAST
ORTHOCHROMATIC ERYTHROBLAST
RETICULOCYTE
EERRYYTTHHRROOCCYYTTEE
E
R
Y
T
H
R
O
P
O
I
E
S
I
S
IL-1,IL-6,IL-3 GM CSF erythro
GM CSF erythro

8. ERYTHROPOIESIS
15-20μm- basophilic cytoplasm,
nucleus with nucleoli.
14-17μm-mitosis, basophilic
cytoplasm, nucleoli
disappears.
10-15μm- ’POLYCHROMASIA’
Hb appears, nucleus
condenses.
7-10μm- PYKNOTIC Nucleus.
Extrusion, Hb is maximum.
7.3μm- Reticulum of basophilic
material in the cytoplasm.
7.2μm- Mature red cell with Hb.

9. STAGES OF ERYTHROPOIESIS
BFU-E CFU-E

10. Proerythroblast
• Earliest erythroid element
• Basophilic cytoplasm with a
perinuclear halo
• Cytoplasm bulges to form
“Ear shaped” process
• Nuclear chromatin is not
homogenous & Nucleolus is seen

11. Basophilic erythroblast/Early normoblast
• Smaller than Proerythroblast
• Nuclear chromatin shows
sharp contrast between light
& dark areas
• Cytoplasm is basophilic
reflecting protein & RNA contents

12. Polychromatophilic
erythroblast/Intermediate normoblast
• Polychromasia means
having many colors
• Nucleus mature & condensed
• Cytoplasm has a gray hue
derived from Hb (Hemoglobin)

13. Orthochromatic erythroblast/Late
normoblast
• Acidophilic erythroblast which is
the last precursor with a nucleus
• Nucleus is compact & situated
near the membrane
• Cytoplasm is like mature red cell,
reflecting a high Hb content

14. Reticulocyte
-Young erythrocytes with granular
or reticular filamentous structures
-Makes up 0.5-2% of all
erythrocytes
-Vital staining required to make
this visible.
-Reticulocytosis seen following
hemolysis or acute blood loss

15. Reticulocyte as seen under the SEM

16. Mature non-nucleated erythrocyte
• Reddish, circular, biconcave cells
• 7-8 μ
• No visible internal structure
• High Hb content
• Bright at centre due to biconcave
shape

17. Erythrocyte as seen under the SEM

18. FACTORS AFFECTING
ERYTHROPOIESIS
 Erythropoietin (EPO): major humoral
regulator of erythropoiesis
 Interleukins, IL3,IL6 & IL1
 Iron
 VitaminB12(Cyanocobalamine)+Folic Acid +
Vitamin C(Ascorbic Acid)
 Intrinsic factor for absorption of B12

19. ERYTHROPOIETIN PRODUCTION
PHSC
PROERYTHROBLAST
ERYTHROCYTE
TISSUE OXYGENATION
EERRYYTTHHROPPOOIIETTIINN
KIDNEY
DECREASES

20. ERYTHROPOEITIN
 Glycoprotein MW-34000.
 90% formed in endothelial cells of the
peritubular capillaries of the renal tubules.
 10% formed in liver, hepatic cells &
Kupffer cells.

21. ERYTHROPOEITIN (contd)
 Stimuli for production
 hypoxia,
 high altitude,
 anemia,
 chronic lung or heart diseases,
 catecholamines,
 prostaglandins &
 androgens.
 Formed in hours, RBC’s take 2-3 days to
appear in peripheral blood.

22. ABSORPTION OF VITAMIN B 12
Intrinsic Factor + Vitamin B12
Vitamin B12 (in a bound state
protected by gastric enzymes)
Binds to mucosal cells of ileum
Absorbed into blood by pinocytosis