Monopoiesis,
Lymphopoiesis, and
Megakaryopoiesis
1
Monopoiesis
2
Monopoiesis
system
consists of monocytes,
macrophages, and their
precursors.
► Monopoiesis is the
formation of mature
monocytes from
monoblasts.
► Primary function of a
monocyte is as a
“scavenger” cell.
Monoblast
► Mononuclear
Promonocyte
Monocyte
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Monoblasts
► Monoblast
has large,
eccentrically placed nucleus.
► Nucleus may be minimally
indented with 1-2 nucleoli.
► Fine lacy nuclear chromatin
in nucleus.
► Cytoplasm is deep blue and
lacks granules.
► N:C ratio is 4:1.
► Cells are non-motile and nonphagocytic.
► Give rise to promonocytes.
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Promonocytes
Promonocytes have large
indented or folded nuclei with
fine chromatin and irregular
margins. May have nucleoli.
► N:C ratio is 3:1 or 2:1.
► Promonocytes slightly
motile. Are rarely phagocytic.
► Will not be required to
identify these cells on
peripheral blood smear.
►
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Monocytes
►
►
►
►
1 of 3
Promonocytes develop into
monocytes.
Enter into peripheral
bloodstream for short period
of time. Then migrate into
tissues to be transformed
into tissue macrophages.
Is large cell (15-18μm). Is
larger than mature
neutrophil.
Have abundant cytoplasm in
relation to nucleus. N:C
ratio is 2:1 or
1:1. Cytoplasm turns dull
gray-blue (dove gray).
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Monocytes
►
►
►
See numerous fine, small reddish
or purplish granules in cytoplasm,
giving it a "ground glass"
appearance.
Occasionally see digestive
vacuoles. In disease states, may
see phagocytized erythrocytes,
nuclei, cell fragments, bacteria,
fungi, or pigments.
Nucleus frequently kidney shaped,
deeply folded or indented; may
occasionally be lobular. Nucleus
has brainlike convolutions. Has
large, delicate chromatin network.
2 of 3
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Monocytes
3 of 3
Shape of monocyte
variable. May see blunt
pseudopods.
► Monocytes have three
morphological
characteristics: brainlike
nuclear convolutions,
blunt pseudopods, and
dull gray cytoplasm.
► Account for 2-9% of
total leukocytes.
►
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Macrophages
►
►
As monocytes move into surrounding
tissues, are converted into
macrophages. Macrophages normally do
not re-enter bloodstream. Are
phagocytic cells.
Macrophages also called histiocytes.
9
Lymphopoiesis
10
Lymphopoiesis
Development from
lymphoblast to a mature
lymphocyte.
► Primary function of
lymphocytes is to protect
against viral infections.
►
Lymphoblast
Prolymphocyte
Lymphocyte
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Lymphoblast
► Lymphoblast
contains
large round nucleus
with small amount of
basophilic cytoplasm.
► Nuclear chromatin
strands are thin, loose,
and evenly
stained. One or more
nucleoli visible.
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Prolymphocytes
► Prolymphocytes
have
intermediate chromatin
clumping. Parachromatin
(reddish purple color)
may be present in
nucleus. Nucleoli may or
may not be present.
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Lymphocytes
►
►
►
►
The lymphocyte progenitor cell can
differentiate into either Blymphocytes (B-cells) or Tlymphocytes (T-cells).
T-cells differentiate in thymus and
B-cells differentiate in bone
marrow.
Do have a third class of
lymphocytes - null cells.
Will not differentiate different
classes of lymphocytes on
peripheral blood smear.
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Reactive Lymphocytes
1 of 3
► Reactive
or atypical
lymphocytes.
► After exposure to
antigen, lymphocytes
transform into
immunologically
competent cells.
► Nucleus and cytoplasm
enlarge. Size varies,
but are usually large
cells with abundant
cytoplasm.
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Reactive Lymphocytes
2 of 3
► Nucleus
may be
indented, oval, or
irregularly shaped with
intermediate
chromatin
pattern. Rarely see
blast-like nucleus with
visible nucleoli.
► See varying degrees of
basophilia. May see
distinctive reddish
granules.
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Reactive Lymphocytes
3 of 3
► Cytoplasm
may
contain vacuoles or
appear bubbly.
► Cell may have
scalloped edges.
► Primarily see in viral
infections.
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Plasma Cell
Formation
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Plasmablasts and Proplasmacytes
► Plasmablast
is similar in appearance to
other blast forms.
► N:C ratio is 4:1.
► Nucleus appears round with fine, linear
chromatin patterns and very visible
nucleoli.
► Seen in multiple myeloma patients.
► Will not be required to identify
plasmablasts or proplasmacytes in
peripheral blood.
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Plasmacytes or Plasma Cells
1 of 3
► Are
end stage of B-cell
development. Not seen
in peripheral blood of
healthy individuals.
► Nucleus usually round or
oval with slightly
irregular margins.
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Plasmacytes or Plasma Cells
2 of 3
► Cytoplasm
non-granular
and stains deep, vibrant
blue (cornflower or
larkspur
blue). Cytoplasm
adjacent to nucleus is
pale with perinuclear
clear zone.
► At cell periphery, have
secretory vesicles. May
see fibrin strands in
cytoplasm.
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Plasmacytes or Plasma Cells
1 of 3
► Nucleus
relatively small,
round or oval, and
eccentrically
placed. Nuclear
chromatin is clumped.
► Produce immunoglobulins
(antibodies).
► Always put up for
pathologist review if
found in peripheral blood.
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Megakaryopoiesis
23
Megakaryopoiesis
► Will
cover this material in MLAB
1227 Coagulation. Are responsible
for morphological characteristics of
mature platelet.
► Are cytoplasmic fragments. Have
no nucleus, Resemble broken
pieces of china. Are often
purple in color.
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25
Bone-Derived Cells
► Not
responsible for this section.
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Molecular
Hematology
27
Introduction to Cell Cycle
► When
stimulated by hematopoietic growth factors,
cells undergo continuous generative cycle (G
cycle) in which cells divide, differentiate, or remain
dormant.
► Bone marrow contains cell populations in all
phases of cell development.
► Cell cycle is divided into five phases: G0, G1, S, G2,
and M.





G0 is resting or dormant phase after cell division.
G1 is postmitotic rest phase.
S is synthesis of DNA phase.
G2 is premitotic rest phase.
M is mitosis phase.
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Multipotential Stem Cells –
Colony Forming Units
► All
cells derived from pluripotential stem cell
which has capacity for continuous selfreplication and differentiation into
multipotential stem cell and lymphoid stem
cell which lack self-replication ability.
► Multipotential stem cell becomes committed
to progenitor cells for each of the cell lines.
29
Colony-Stimulating Factors
and Interleukins
► Each
cell line dependent on
cytokines. Cytokines are soluble
mediators secreted by cells for purpose of
cell-to-cell communication.
► Act on multipotential cells to stimulate their
proliferation and differentiation.
► Two types of cytokines are colonystimulating factors or growth factors and
interleukins.
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Trends in Therapeutic Manipulation
of Hematopoiesis
► This
section will be covered in MLAB 1335.
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1. Study Questions
2. Homework Assignment
3. Exam for Unit I will be
on Sept 13
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