Erythropoiesis is the process where red blood cells develop from stem cells in the bone marrow. It proceeds through several stages, starting with stem cells that differentiate into progenitor cells and then normoblasts as the cells mature. Key changes occur like decreasing size, loss of nucleus and organelles, and increasing hemoglobin content. Erythropoietin is the main hormone that stimulates and regulates red blood cell production in response to hypoxia. Other factors like iron, vitamin B12, and folic acid are also necessary for erythropoiesis.

1. ERYTHROPOIESIS

2. ERYTHROPOIESIS

3. CONTENTS
1. Definition
2. Sites of erythropoiesis
3. Stages of erythropoiesis
4. Factors affecting Erythropoiesis
5. Erythropoietin
6. HYPOXIA
7. FOLIC ACID
8. Vitamin B12
9. CLINICAL ASPECTS
10. SUMMARY

4. It is the process of development,
differentiation and maturation of RBCs
from primitive stem cells
DEFINITION

5. SITESOFHAEMOPOIESIS.
 First2 monthsof
gestation –yolk sac.
 3rdmonthonwards –
liver 7 spleen.
 20thweek onwards –
till birth - bone
marrow.
Monday, December 7,
2015

6. SITESOFHAEMOPOIESIS.

s



• InYoungChildren–axial skeleton & bones of
extremitie
• i.e. Red Bone marrow.
• With fatty replacement it becomes Yellow Bone
Marrow.
• In Adults – axial skeleton & proximal
extremities of long bones.
• InPathological conditions –extra
medullary haemopoiesis

7. HAEMOPOIESIS

9. 1. STEM CELLS
 These cells have extensive proliferative capacity
and also the:
 Ability to give rise to new stem cells(Self
Renewal)
 Ability to differentiate into any blood cells lines
(Pluripotency)
 Hematopoietic stem cells (HSCs) are bone
marrow cells that are capable of producing all
types of blood cells.
 They differentiate into one or another type of
committed stem cells (progenitor cells).

10. 2. Progenitor cells BFU-E & CFU-E
 BFU-E Give rise each to
thousands of nucleated
erythroid precursor cells.
 Undergo some changes to
become the Colony
Forming Units-Erythrocyte
(CFU-E)
 Regulator: Burst
Promoting Activity (BPA)
 Committed stem cells
lose their capacity for
self- renewal.
 They become
irreversibly
committed.

11. Burst forming unit BFU(E)
 Unipotent progenitor cell
 Less sensitive to erythropoietin
 Responds to other
stimulus forms
Colony forming unit CFU (e)
 Highly sensitive and dependent on
erythropoietin

12. 3. Proerythroblast
• 15-20 microns
• Nucleus with
multiple
nucleoli
• Basophilic
cytoplasm
with
perinuclear halo
• No hemoglobin

13. 4. Basophilic/ early normoblast
 Slight reduction in
size 14-17µm
 Large nucleus,
nucleoli reduce in
number
 Basophilic cytoplasm
 Active mitosis

14. 5. Polychromatophilic/ intermediate
normoblast
 10-15µm size
 ’POLYCHROMASIA’
 nucleus condenses
Chromatin lumps
 Hb starts appearing
 Reduced mitoses

15. 6. Orthochromatic normoblast
•7-10µm
•Acidophilic erythroblast
which is the last precursor
with a nucleus.
•Nucleus is compact &
situated near the membrane
pyknotic nucleus is extruded
•Cytoplasm is like mature red
cell, reflecting a high Hb
content.
•Mitosis absent

16. 7. Reticulocyte
 Reticular nuclear
fragments
 Nucleus extruded
 Slightly larger than RBCs

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

18. CELLS/FEATURES SIZE CYTOPLASM NUCLEUS
HAEMOGLO
B IN
MITOSIS
PRONORMOBL
AS T
15-20
μm
BASOPHILIC
LARGE
WITH
RETICULA
R
FORMATIO
N
ABSENT SEEN
LARGE,NUC
L
EARLY 12- BASOPHILIC EOLI ABSENT SEEN
16μm DISAPPEAR
E
D.
INTERMEDIATE
10-
14μm
POLYCHROM
ATIC
CONDENSE
D
APPEARS PRESENT
LATE 8-10μm
ACIDOPHILI C SMALL
PYKNO
TIC
INCREASES ABSENT
RETICULOCYTE
7-
7.5μm
RETICULUM
LIKE
ABSENT INCREASES ABSENT

19. Changes during erythropoiesis
 Decrease insize
 Loss of mitotic activity (later partof
intermediate.normo)
 Hemoglobinization(intermediate
normoblast)
 Change of cell shape (from globularto
biconcave)
 Disappearance of nucleus,mitochondria,
RNA, etc
 Change of staining (basophilic–
eosinophilic)

20. Regulation of erythropoiesis
 General factors
-
-
• - Hypoxia  erythropoietin Growth inducers
• Vitamins
 Maturation factors
- Vitamin B 12
- Folic acid
 Factors necessary for hemoglobin production
- Vitamin C Helps in iron absorption (Fe+++  Fe++)
- Proteins  Amino Acids for globin synthesis
- calcium, bile salts, cobalt & nickel.

21. ERYTHROPOIETIN
 Glycoprotein MW-34000 (165 AA residues)
Formation
 85% formed in endothelial cells of the
peritubular capillaries of the renal tubules.
 15% formed in liver, hepatic cells & Kupffer
cells.
Breakdown
 In liver. Half life is 5hours

22. ERYTHROPOEITIN
r heart
Stimuli for production
 Hypoxia
 Products of RBC
destruction
 High altitude
 Anemia
 Chronic lung o
diseases
 Catecholamines
 Prostaglandins
Androgens

23. EFFECT OF HYPOXIA

24. VITB12
 VitB12 –
Cyanocobalaminor
extrinsic factor.
 Dailyneed–1-2 μg.
 Sources–Milk, Meat,
Liver of Animals
 Also synthesized by
bacterial Flora.

25. LIFE SPAN OF MEGALOBLAST IS 40 DAYS

26. FOLICACID
 Folicacid–
Pteroylglutamic acid.
 Dailyrequirement–
100 μg.
 Sources–leafy veg,
pulses, yeasts, liver.
 From breakdown of
Polyglutamate to
Monoglutamates.

27. Clinical Aspects
Anemias: ReducedRBCcount /reduced Hb
concentration
Polycythemia: Increased RBCcount
 Polycythemia vera
 Secondary polycythemia- due tohypoxia

28. SUMMARY

29. BIBLIOGRAPHY
1. Guyton and Hall Textbook of Medical Physiology E-Book
(Guyton Physiology)
2. Essentials of Medical Physiology by k.sembulingum
3. Google
4. TEXTBOOK OF PHYSIOLOGY BY AK JAIN
5. Ganongs Review Of Medical Physiology 25th Edition

30. THANK YOU