1. FORMATION OF WHITE BLOOD CELLS
Dr. B.L. Mtinangi.
Department of Physiology
School of Medicine, MUHAS
November, 2015

2. FORMATION OF WBC
As for the Rbc, the formation of Wbc originates from the COMMON PROGENITOR CELL ie uncognisable cell which develop to the UNCOMMITTED STERM CELL and this changes to COMMITTED STERM CELL

4. FORMATION OF WBC CONT. Committed sterm cell can either develop into:
Myeloblast series or
Monoblast or
Lymphoblast series.
Myeloblast changes into Promyelocyte & the Promyelocyte to Myelocyte which will either develop into
NEUTROPHIL or BASOPHIL or EOSINOPHIL.

6. FORMATION OF WBC CONT. Monoblast develop into:
Monocyte in the circulating blood
Tissue Macrophage ie the Monocyte that has moved into various tissues.
Lymphoblast from Lymphogenous organs develop into Prolymphocyte which will then develop into:
Large Lymphocyte &
Small Lymphocyte

9. WBC CONT.
White blood cells are Leucocytes & Macrophages that are involved in the defence mechanisms against:
Bacteria
Viruses
Fungus &
Parasites

10. WBC CONT. Mechanism of action of Wbc is either
Phagocytic eg neutrophil, eosinophil, basophil & monocytes OR
Antibodies formation eg lymphocytes
Wbc are of two types:
With granules (Granulocytes)
Without granules (Agranulocytes)
Normal Wbc count ranges from 4000 to 11000/micro litre

11. WBC CONT. Wbc with granules (granulocytes) are
Neutrophils 40 – 70% (60%)
Eosinophil – 4% (3%)
Basophil % (1%)
Wbc without granules (agranulocytes)
Lymphocytes 20 – 45% (30%)
Monocytes % (6%)
NB. Platelets are sometimes grouped as Wbc

13. FUNCTIONS OF WBC Granulocytes and Monocytes are for PHAGOCYTOSIS
Lymphocytes are for IMMUNITY ie
Cell mediated immunity &
Antibody formation
Platelets are for blood clotting (COAGULATION) mechanisms

14. Type Of White Blood Cells Lymphocytes (B Cells and T Cells)
% By Volume Of WBC
Description
Function
Neutrophils
60 – 70 %
Nucleus has many interconnected lobes; blue granules
Phagocytize and destory bacteria; most numerous WBC
Eosinophils
2 – 4 %
Nucleus has bilobed nuclei; red or yellow granules containing digestive enzymes
Play a role in ending allergic reactions
Basophils
< 1 %
Bilobed nuclei hidden by large purple granules full of chemical mediators of inflammation
Function in inflammation medication; similar in function to mast cells
Lymphocytes (B Cells and T Cells)
20 – 25 %
Dense, purple staining, round nucleus; little cytoplasm
the most important cells of the immune system; effective in fighting infectious organisms; act against a specific foreign molecule (antigen)
Monocytes
4 – 8 %
Largest leukocyte; kidney shaped nucleus
Transform into macrophages; phagocytic cells

15. WBC CHARACTERISTICS
Each Wbc has specific distinguishing characteristics in terms of:
Cell size
The shape of Nuclear
Cytoplasmic content
Type of granules &
Phagocytic activity of the cell

16. LIFE SPAN OF WBC
The life span of the Wbc differs depending on the type of Wbc:
Granulocytes have a life span of 4 to 8 hrs in the circulation and 4 to 5 days in tissues
Monocytes have a short transit in circulation then go to TISSUES as Tissue macrophages
Lymphocytes have a life span of about 100 to 300 days, tend to recirculate. Some are known to have a life span of 7 years

17. MECHANISM OF CELL PHAGOCYTOSIS
Margination ie lining of cells(Wbc) on the capillaries due to bacteria products or toxins
Diapedesis ie squeezing through small pores in blood capillaries
Migration ie ameboid or psedopodia motion esp Neutrophils & macrophages
Chemotaxis ie movements due to bacteria toxins & inflammation.
All cause a directional migration of NEUTROPHIL & MACROPHAGES to the site of injury or infection

18. PHAGOCYTOSIS CONT. The process of phagocytosis:
Bacteria are ENGULFED by Pseudopodia & Fusion
Bacteria then lies within a cel l vacuole with phagosome
Lysosomal or digestive enzymes are secreted into phagosome causing
Degranulation & Lysis of the bacteria leading to DEATH

19. BREAK