Blood is a fluid tissue with a complex structure. Blood consists of plasma (55%) and blood cells (45%). Blood cells are of three types. i.e. RBC, WBC & Platelets. WBC: WBC also known as Leucocytes. Do not possess any pigment, they appear colorless. Provide immunity to the body, is the main function of WBC.

1. White Blood Cells
or
Leukocytes
Amjad KhanAfridi
Chapter # 07

2.  Blood is a fluid tissue with a complex structure.
 Blood consists of plasma (55%) and blood cells (45%).
 Blood cells are of three types. i.e.
RBC, WBC & Platelets.
WBC: WBC also known as Leucocytes.
 Do not possess any pigment, they appear colorless.
 Provide immunity to the body, is the main function of
WBC.

3. On the based of granules, Leukocytes are
divided into two major groups;
1. Granulocytes and 2. agranulocytes,
which are based on their cytoplasmic
granules.
• Neutrophils, Eosinophils and
Basophils are the granular leucocytes
which have granules in their
cytoplasm.
• Lymphocyte and Monocyte are the
agranular leucocytes which lacks of
Granulocytes
Agranulocytes

4. 1. Granulocytes
• Granulocytes are a group of white blood cells that are
characterized by the presence of cytoplasmic granules.
• All granulocytes are differentiated cells with a life span of only a
few days.
• The cell contains Golgi complexes and rough ER that are poorly
developed, with few mitochondria mainly needed for glycolysis to
meet their energy needs.
• Granulocytes are further divided into neutrophils, eosinophils and
basophils depending on their reaction to different dyes.
Granulocytes

5. A. EOSINOPHILS
• Eosinophils are granulocytes with a bilobed
nucleus that can be differentiated from other
leukocytes based on the presence of abundant
large, acidophilic specific granules typically
staining pink or red.
• Size ranging from 10 to 15 microns in diameter
• Eosinophils also modulate inflammatory
responses by releasing chemokines & cytokines.
• These cells are capable of phagocytizing foreign
bodies.

6. B. BASOPHILS
• Basophils are blood cells in which the nucleus is
divided into two irregular lobes, with specific
cytoplasmic granules that typically stain purple with the
basic dyes.
• Size ranging from 10 to 15 microns in diameter
• The granules are fewer, larger, and more irregularly
shaped than the granules of other granulocytes.
• Basophilic granules also contain much histamine and
various other mediators of inflammation, including
platelet-activating factor, eosinophil chemotactic factor,

7. C. NEUTROPHILS
• Neutrophils are small, fast, and active scavengers protect the body
against bacterial invasion and remove dead cells and debris from
damaged tissues.
• The nucleus is frequently multi-lobed with lobes connected by thin
nuclear extension, and their granules are lysosomes containing
enzymes to digest engulfed material.
• Size ranging from 10 to 15 microns in diameter
• Accounts for 50-70% of all leucocytes

8. • The lifespan of neutrophils is an average of 6–9 hours in the
bloodstream, and their numbers rise very quickly in an area of
damaged or infected tissue.
• The neutrophils are attracted in large numbers to any area of
infection by chemicals called chemotaxins, released by damaged
cells.
• Neutrophils are highly motile so that they can squeeze through the
capillary walls in the affected area by the process called diapedesis.
• Neutrophils are the first leukocytes to reach the sites of infection
where they actively pursue bacterial cells using chemotaxis and
remove the invaders or their debris by phagocytosis.

9. 2. Agranulocytes
• Agranulocytes lack specific granules but do
contain some azurophilic granules
(lysosomes). The nucleus is spherical or
indented but not lobulated.
• Leukocytes play an essential role in the
constant defense against invading
microorganisms and in the repair of injured
tissues.
• Agranulocytes include the lymphocytes and
monocytes, both of which crucial against
antigens and pathogenic microorganisms.

11. • Lymphocytes are round cells that contain a
single, large round nucleus. There are two
main classes of lymphocytic cells; the B cells
that mature in the bone marrow, and the T-
cells that mature in the thymus gland.
• Lymphocytes are typically the smallest
leukocytes and constitute approximately a
third of these cells.
• Although generally small, circulating
lymphocytes have a wider range of sizes than
most leukocytes.
A. Lymphocytes

12. • Monocytes are agranulocytes that are the largest
of all white blood cells, some of which also act as
precursor cells of macrophages, osteoclasts,
microglia, and other cells of the mononuclear
phagocyte system in connective tissue.
• Circulating monocytes have diameters of 12-15
μm, but macrophages are often somewhat larger.
B. Monocytes

13. b. Monocytes

14. 30th December, 2021