Stages of Development of
Blood Cells
Dr. Sama ul Haque
Dr Rania Gabr
Objectives
• Understand the composition of whole blood.
• How to prepare a blood smear.
• Describe the structure of Erythrocyte.
• Enlist different types of leucocytes.
• Explain the differentiation of myeloid and lymphoid stem
cells.
• Discuss the development of blood cells in red bone marrow.
Composition of Whole Blood
Preparing a Blood Smear
Formed elements
Red Blood cells
White blood cells
Granulocytes
(Polymorphonucleated)
Neutrophils
Platelets
Basophils
Eosinophils
Agranuloctes
(Mononucleated)
Lymphocytes
Monocytes
Blood Cells
Blood Cells
ERYTHROCYTE
• These cells are:
• biconcave disk
•no nucleus
•~7.8 μm diameter fresh;
• 7.2 -7.4 in stained smears
•contains hemoglobin
The primary function of these cells
is to carry oxygen from the lungs to
the body cells.
Normally: (4-6 million )erythrocytes
per cubic millimeter of blood,
Erythrocyte
Normal Human Erythrocyte
• Diameters greater than 9 um are
called:
“MACROCTES”
Diameters less than 6 um are called:
“ MICROCYTES”
• Sickle cell anemia is an inherited
condition which results in some
erythrocytes being malformed.
• The gene for this condition causes
the hemoglobin to be incorrectly
formed, which in turn causes some
erythrocytes to take on a crescent
shape.
• These cells are not able to carry
adequate amounts of oxygen to
cells.
Leukocytes (6-10,000 per μL)
• Granulocytes (polymorphonuclear leukocytes):
–Neutrophils -60-70%
–Eosinophils -2-4%
–Basophils -0.5-1%
• •Agranulocytes (mononuclear leukocytes)
–Lymphocytes -20-30%
–Monocytes -3-8%
Types of Human Leucocytes
Neutrophils, eosinophils, and basophils have granules that stain specifically with
certain dyes and are called granulocytes. Lymphocytes and monocytes are
considered agranulocytes, even though they may show azurophilic granules
(lysosomes), which are also present in other leukocytes.
Neutrophils
Neutrophils can be identified by their multilobulated nuclei, with lobules held together
by thin strands. With this feature the cells are often called polymorphonuclear
leukocytes, or just polymorphs.
These cells are capable
of phagocytizing
foreign cells, toxins,
and viruses.
When taking a Differential WBC Count of normal blood,
this type of cell would be the most numerous.
Normally, neutrophils account for 60-70% of all
leukocytes.
If the count exceeds this amount(Neutrophilia), the
cause is usually due to an acute infection such as
appendicitis, smallpox or rheumatic fever.
If the count is considerably less(Neutropenia), it may
be due to a viral infection such as influenza, hepatitis,
or rubella.
Eosinophils
Eosinophils are about the same size as neutrophils but have bilobed nuclei and
abundant coarse cytoplasmic granules. The cytoplasm is often filled with brightly
eosinophilic specific granules, but also includes some azurophilic granules. (a): A
eosinophil next to a neutrophil for comparison with its nucleus and granules. (b): Even
with granules filling the cytoplasm, the two nuclear lobes of eosinophils are usually
clear.
(Does it look like a telephone
receiver?)
• Function:
1- The granules contain digestive enzymes that are
particularly effective against parasitic worms in their
larval form.
2- These cells also phagocytize (antigen - antibody
complexes).
These cells account for less than 5% of the WBC's.
Increases beyond this amount(Eosinopilia): may be due
to parasitic diseases, bronchial asthma or hay fever.
Eosinopenia may occur when the body is severely
stressed.
Basophils
Approximately the same size as neutrophils and eosinophils, but have large, strongly
basophilic specific granules which usually obstruct the appearance of the nucleus
having two or three irregular lobes.
These granules contain histamines
(cause vasodilation) and heparin
(anticoagulant).
Lymphocytes
Lymphocytes are agranulocytes and lack the specific granules characteristic of
granulocytes. (a): Small lymphocytes are slightly larger than the neighboring
erythrocytes with spherical nucleus. (b): Medium lymphocytes are distinctly larger than
erythrocytes. (c): Large lymphocytes, much larger than erythrocytes.
Round, dark,
heterochromatic nucleus –
like an “ink spot“
These cells play an
important role in our
immune response.
Monocytes
Monocytes are large agranulocytes that circulate as precursors to macrophages and
other cells of the mononuclear phagocyte system. Monocytes show their eccentric
nuclei indented, kidney shaped, or U shaped. The largest leucocyte.
Platelets
Platelets are cell fragments 2–4 µm in diameter derived from megakaryocytes of
bone marrow. Their primary function is to rapidly release the content of their granules
upon contact with collagen to begin the process of clot formation and reduce blood loss
from the vasculature. Platelets (arrows) are often found as aggregates.
Summary of Formed Elements
Differentiation of
Myeloid And
Lymphoid Stem
Cells
1. EPO– Erythropoietin
2. CSF– Colony
Stimulating Factor
3. GM-CSF–
Granulocyte+Macrophage
CSF
4. M-CSF– Macrophage CSF
5. G-CSF– Granulocyte CSF
Differentiation of Myeloid And Lymphoid Stem Cells
Development of Blood Cells in Red Bone Marrow
Thank You