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Granulocytes
 They are non- granular and referred to as mononuclear
leukocytes.
 They contain the specific granules, but frequently
contain azurphilic granules (stain with azure dyes).
Which are characterisly for lysosomes (primary)
Monocytes
% of total leukocytes 3 – 8%
Origin = monoblast
Diameter = 9 - 15 = the largest cell of WBC
Nucleus: it is large indented nucleus (kidney or horseshoe
shaped)
 The indentation here is prominent than in lymphocytes.
EM = the indentation contain mainly Golgi and centrioles.
Stain usually less compact than lymphocyte.
Cytoplasmic granules
Contains small number of azurphilic granules that contain
Hydrolytic enzymes.
Functional consideration
1- They are highly phagocytic cells. They are transiently
found in the circulation.
2- They differentiate in connective tissues to
macrophages.
which are highly mobile and exhibit? Pseudopodia their
name in different connective tissues are:
1- in C. T
Histocytes
2- in liver
Cupffer cells
3- in lung
Alveolar macrophages
macrophayse in spleen, lymphrod and bone marrow
 At the site of inflammation
monocyte leave the
circulation
C.T and now called macrophages that
participate in phagocytosis of bacteria and tissue debris.
 It concentrated antigen and presented it to the lymphocytes
 Monocytes increase in chronic inflammation TB, syphilis,
typhus.
Lymphocytes:
They are concern with immune system.
% Of total leukocytes 20 - 40 %
Diameter = range from 6 - 18 Mm
According to this size, they are dividing into smaller, medium
and large.
The small lymphocytes formed the most majority 79 %
They are 5-8 M medium 10-12 large 14-15
The small lymphocytes represent the mature lymphocytes.
Nucleus
Small here single, large, spherical, may have slightly
indented nucleus.
 They are intensely stained and surrounded by faint (
blue) rim of cytoplasm due to free ribosome's
 Hetero chromatic nucleus and occasionally azurphilic
granules
Medium and large size lymphocytes here relatively voluminous
Cytoplasm (small with small rim of cytoplasm, large with wider
rim of cytoplasm.
Medium and small size lymphocytes
present mainly in
peripheral blood and lymphoid tissues
Large size lymphocytes
present in mainly lymphoid tissue
and rarely in blood.
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Functional classification of lymphocytes
T &B lymphocytes
T cells = T lymphocytes = derived from thymus dependent
lymphocyte
 Constitute 70 % of circulating lymphocytes
 Here longer live span and involve in cell mediated immunity
and increase in chronic infection such as TB, syphilis, viral
cancer.
 Long lived lymphocytes may survive for months or years
They are thought to be memory cells.
B cells = B lymphocytes = have variable life span first discovered
in the bursa of fabrics in bird.
It is responsible for production of antibodies humoral immunity
B + T lymphocytes are only differentiated by immunohistochomical
staining by detecting their surface receptors
Three types of T lymphocytes
1- Cytotoxic lymphocyte = killer Tk = Tk recognize other
Cells that have foreign antigen (especially) on their
surface
then release lymphokinase to kill the
antigen. Antigen
recognize by T. C
stimulate Tk to be
produced and become synthesized.
2- Helper T lymphocyte (T H) recognizes the antigen or
foreign body and help B cell + macrophages to participate
in immune reaction
3- Suppress T cells (T s cells) ~ this act to suppress the
immune response to normal or self molecule thus
suppresses action of T and B cells.
T cells participation - graft - rejection
B lymphocytes =
Antigen
recognized by memory or sensitized T cells
Stimulate helper cell
chemotact and activity of B cells
B cell enlarges and differentiates into plasma cells
secrete
antigen antibody that reacts specifically to original antigen for
each antigen special type of antibody either to bacteria or its
toxin.
NB = Not all the activated B cells will transform into plasma cells
Majority will form memory B lymphocytes to respond to
antigen if exposed again
Platelets
They are the smallest formed elements of blood
2 - 4 Mm in length
They hare flat bi-convex disk shaped (like lens)
They are cytoplamic fragments of megakaryocytes
Each megakaryocytes produce 1000 - 5000 platelets
In blood smear, they appear as single or in clusters –
lifespan about 10 days
 With LM + EM two regions of cytoplasm are distinguishable
a- The center region or zone = granulomere
b- The peripheral cytoplasm surrounds by hyalomere
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EM = contain microtubules and actin filaments.
In the granules: 3 types could be seen:
1- α = granules = platelets specific protein such as
Fibrinogen and clotting factor
2- Dense granules = contain vasoconstriction, ADP, ATP
and calcium.
3-Lysosome.
Formation of clot: If there is injury to the endothelium of blood
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Prothrombin
vessels
Platelets change its shape and aggregate at the
site of injury
Platelets adhesion and changing in shape
Degranulated and release ADP & serratonin which
are potent vasoconstrictor. also ADP formed
thrombaxan
platelets +
thrombin fibrinogen fibrin
clotting factor
Actin, microtubules + myosin, glycogen also help in clot
retraction. Platelets also contain thrombosthein - similar to
contractile protein cutomyosin of muscle.
During processes of healing plasma protein plasminogen convert
into plasmin, which dissolve the blood clot.