the RBC production and maturation completed in the bone marrow normally, all the maturation stages of erythropoiesis are descriped here and how regulated ..etc

1. Red Blood Cells Production
Hematopoiesis
Developed by Dr.
Abdulrazzak Othman Alagbare - Clinical Pathologist
Hematology Lecturer

2. Erythropoiesis
Definition: it is a process of erythrocytes production.
Erythropoiesis produces 2.5 million RBCs/second from stem cells
(hemocytoblasts) in bone marrow
Production site:
1- RBC Formation before birth
A. Mesoblastic stage  Nucleated RBCs
B. Hepatic stage  all blood cells
C. Myeloid stage  all blood cells
Site Cells production

3. RBC Formation after birth
1. From the birth up to 5years old 
All the bones produce blood cells
(long bones and sternum)
2. After the 5th years only in 
Vertebrae, Sternum, Ribs, and
Ilium.

5. Synthesis requirements for RBC production needs
 Iron
 Protein
 Vitamin B12 and B6 Folic acid and Vitamin
C and E
 copper (for cofactors for enzymes
synthesizing RBCs)
 Erythropoietin hormone (EPO)

6. Erythropoietin hormone (EPO)
 Nature: Glycoprotein  Human
erythropoietin is a 193-amino acid
glycoprotein.
 The responsible gene located on the
chromosome 7
 Sources : 90% from the kidneys and 10%
from the liver
 Activity: stimulate and regulate the bone

7. Regulation of erythropoiesis
The erythrocytes production regulated by
1-Erythropoietin hormone (EPO)
2-Level of oxygen in the tissues
Stimuli for erythropoiesis
Low levels of O2
Increase in exercise
Hemorrhaging
increase production of
erythrocytes

8. Erythrocytes Maturation steps are
Erythrocytes consist 10-30% of all
hematopooietic cells in the bone marrow
Production Site: only in the bone
marrow
Target: synthesis of
1. Hemoglobin (Hb)
2. Enzymes such as
 Glucose 6 dehydrogenase
phosphate (G6PD)
 and pyruvate kinase (PK)
Period: about 8-10 days

9. Erythrocytes Maturation
sequence of the formation
of red blood cells
(Erythropoiesis)
• Pronormoblast
• Early normoblast
• Intermediate normoblast
• late normoblast
• Reticulocyte mature
Erythrocyte

11. (1) Pronormoblast:-
• No hemoglobin
• Nucleus 12 um
• Contain nucleoli
(2) Early - normoblast:-
 Nucleoli disappear
 Hemoglobin starts
appearing – Little Hb

12. (3) Intermediate -
normoblast:-
 Cytoplasm deep blue
 Increase in RNA
 Increase Hemoglobin
synthesis
(4) Late -normoblast:-
 Nucleus smaller-
pyknosis
 And Nuclear
extrusion

13. (5) Reticulocyte:-
Remnant of RNA  Synthesizing
proteins and Hb continue 34%
Consist about 1 % of Red Cells

14. 5-Reticulocytes:
Reticulocytes
contain
ribonucleic acid
(RNA) for 4
days;
normally, the
first 3 days are
spent in the
marrow and
fourth in the

15. (6) Erythrocytes:-
 Round, biconcave,
disc shaped.
 Diameter 7.8 um.
 Can deform easily.
Transfer of RBC to Circulation
RBC transfers into the peripheral blood by (Diapedesis)
Diapedesis: Process by which Erythrocytes come out of
blood vessel wall
a) Pores of vessel wall are smaller than cells
b) Small portion of the cell squeezes through the pores

16. Maturation affect on the
Erythrocytes production
1-synthesis of
hemoglobin
2-Synthesis of the
main enzymes (G6PD
and PK)
3-Loss of the nucleus
in the late normoblast
step

17. RBC properties in the peripheral
blood
1. Non nucleated
2. Flexible biconcave disc
3. lives 100-120 days in the
circulation.
4. Function transport of 02 to the
tissue and remove the CO2
5. Aged red cells removed by
the spleen

18. END OF THE LESSON