2. What did the word ( hemopoiesis ) mean ?
• (Gr. haima , blood + poiesis , a making)
Blood formation
3. Stem cells
• pluripotent cells capable of asymmetric division and
self-renewal.
When a stem cells divide, they give at the same time
1.specifi c, irreversibly differentiated cell types.
2. Pools for slowly dividing stem cells ( self renewal ).
4. Hemopoietic stem cells
• It is simply stem cells that found in bone marrow.
• This type of cells are rare
5. Blood formation during life
Hemopoietic bonemarrow occurs in many locations through
puberty, but then becomes increasingly restricted to
components of the axial skeleton.
7. Progenitor cells
• The progenitor cells for blood cells are commonly called
colony-forming units (CFUs), because they give rise to
colonies of only one cell type
there are four major types of progenitor cells/CFUs:
1- Erythroid lineage
2- Thrombocytic lineage
3- Granulocyte-monocyte lineage
4- Lymphoid lineage
8. Precursor cells
• Each progenitor cell/CFU lineage produces precursor
cells (or blasts) that gradually assume the
morphologic characteristics of the mature,
functional cell types they will become In contrast, stem
and progenitor cells cannot be morphologically
distinguished and simply resemble large
lymphocytes.
9.
10. Colony stimulating
factors
Factors that stimulate production of one cell line (
type ) in the bone marrow .
They also called “ cytokines “
They are glycoproteins that stimulate proliferation of
progenitor and precursor cells and promote cell
differentiation and maturation within specific lineages
11.
12. Bone marrow
Found in medullary canals of long
bones and small cavities of
cancellous bone
Tow types
1- red bine marrow
2- yellow bone marrow due to
accumulation of fat ( adibocyte )
Bone marrow contain
1- reticular connective tissue stroma 2-
hemopoietic cords or islands ( c )
3- sinusoidal capillaries
The hematopoietic niche in
marrow includes the stroma,
osteoblasts, and megakeryocytes
Between the hematopoietic
cords run the sinusoids, which have
discontinuous endothelium, through
which newly blood cells and platelets
enter the circulation
13.
14. Maturation of erythrocyte
1- Micrographs showing a very
large and scarce proerythroblast
(P)
2- a slightly smaller basophilic
erythroblast (B) with very
basophilic cytoplasm
15. 3-typical and late polychromatophilic
erythroblasts (Pea nd LPe) with both basophilic
and acidophilic cytoplasmic regions
4- small orthochromatophilic
erythroblast (Oe) with cytoplasm nearly like
that of the mature erythrocytes in the field
5- reticulocytes (arrows) that have not yet
completely lost the polyribosomes used to
synthesize globin, as demonstrated by a stain
for RNA
16. So in the maturation of erythrocyte,
size of cell ( decrease )
size of nucleus ( decrease )
Basophilia ( decrease )
eosinophilia ( increase )
organelles ( disappeared )
nucleus ( extrusion )
polysome ( disappeared in Pe )
ribosome ( disappeared in R to Er )
17. The source of basophilia ( decreased ) in stages of
maturation erythrocyte is from
1- polysomes
2- RER
The source of eosinophilia ( increased ) in stages of
maturation erythrocyte is from hemoglobin
18. • Reticulocyte constitute 1% of the red blood cells
quickly lose the polyribosomes, and mature as
erythrocytes.
21. Ertrhrocyte cell membrane
• The cell membrane of RBCs is well developed and
organized because of its function ( to exchange )
• cell membrane consist of 40% lipid, 50% protein, and 10%
carbohydrate
• Most of the latter are integral membrane proteins
1- glycophorin A. ( basis of ABO blood typing system )
2- band 3 protein ( ion transport )
• Several peripheral proteins are associated with the inner
surface of the membrane include ( spectrin , ankyrin )
• This submembranous meshwork stabilizes the membrane,
maintains the cell shape, and provides the cell elasticity
required for passage through capillaries.
22. Clinical correlates
• Low number of erythrocyte in the circulation or
low amount of hemoglobin in the RBCs will
lead to anemia
• High number of erythrocyte in the circulation is
called polycythemia
25. Neutroplils
• neutrophilic granulocyte passes through an intermediate
stage, the band cell (or stab cell), in which the nucleus
is elongated but not yet polymorphic.
• The appearance of large numbers of immature
neutrophilsn(band cells) in the blood, sometimes
called a “shift to the left,” is clinically significant, usually
indicating a bacterial infection.
26. - Larger than erythrocyte
- Mutilobulated ( 3-5 )
- Also called polymorphonuclear leukocytes
- Micrograph showing a neutrophil from a female in which the condensed X chromosome
appears as a drumstick appendage to a nuclear lobe (arrow)
27. Eosinophils
-Eosinophils are about the same size as neutrophils but have bilobed nuclei and more
abundant coarse cytoplasmic granules. The cytoplasm is often filled with brightly
eosinophilic specific granules, but it also includes some azurophilic granules.
-Micrograph shows an eosinophil (E) next to a neutrophil (N) and a small lymphocyte (L).
- Even with granules filling the cytoplasm, the two nuclear lobes of eosinophils are usually
clear.
28. Clinical correlate
• An increase in the number of eosinophils in blood
(eosinophilia) is associated with
1- allergic reactions and,
2- helminth parasitic infections.
• In patients with such conditions,
• eosinophils are found in the connective tissues
underlying epithelia of the bronchi, gastrointestinal
tract, uterus, and vagina, and surrounding any
parasitic worms present.
29. Basophils
• Basophils are also approximately the same size as neutrophils and
eosinophils,
• they have large, strongly basophilic specific granules that usually obstruct
the appearance of the nucleus which usually has two large irregular lobes.
30. Clinical correlate
• In some individuals a second exposure to a strong
allergen, such as that delivered in a bee sting, may
produce an intense, adverse systemic response.
• Basophils and mast cells may rapidly degranulate,
producing vasodilation in many organs, a sudden
drop in blood pressure, and other effects
comprising a potentially lethal condition called
anaphylaxis or anaphylactic shock.
32. Monopoiesis
• The monoblast is a committed progenitor
cell that is virtually identical to the
myeloblast morphologically
• Further differentiation leads to the
promonocyte, a large cell with
basophilic cytoplasm and a large,
slightly indented nucleus
• chromatin is lacy and nucleoli are
evident.
• Promonocytes divide twice as they
develop into monocytes.
33. Monocyte
• Monocytes are large agranulocytes with diameters
from 12 to 20 μm that circulate as precursors to
macrophages andother cells of the mononuclear
phagocyte system.
• Micrographs of monocytes showing their
distinctive nuclei which are indented, kidney-
shaped, or C-shaped.
• Differentiating monocytes contain extensive RER
and large Golgi complexes forming lysosomes,
which are observed as fine azurophilic granules
at maturity.
• Monocytes circulate in blood for several hours
and enter tissues where they mature as
macrophages (or other phagocytic cells) and
function for up to several months.
34. Clinical correlate
• Extravasation or the accumulation of immigrating
monocytes occurs in the early phase of inflammation
following tissue injury.
• Acute inflammation is usually short-lived as
macrophages undergo apoptosis or leave the site
• chronic inflammation usually involves the continued
recruitment of monocytes. The resulting continuous
presence of macrophages can lead to excessive tissue
damage that is typical of chronic inflammation.
36. Lymphocytopoiesis
• all lymphocyte progenitor cells originate in the bone
marrow
• Some of these lymphocytes migrate to the thymus,
where they acquire the properties of T lymphocytes.
• Subsequently, T lymphocytes populate specific regions
of peripheral lymphoid organs
• Other bone marrow lymphocytes differentiate into B
lymphocytes in the bone marrow and then
• migrate to peripheral lymphoid organs, where they
inhabit and multiply within their own niches.
37. • The first identifiable progenitor of lymphoid cells is the lymphoblast.
• Lymphoblast is a large cell capable of dividing two or three
• times to form lymphocytes
• As lymphocytes develop, their nuclei become smaller, nucleoli
become less visible, and the cells decrease in size overall.
• In the bone marrow and in the thymus, these cells synthesize the
specific cell surface proteins that characterize B or T
lymphocytes,
• respectively. Mature and functionally active B and T cells are
generally larger than newly formed lymphocytes.
38. Lymphocyte
Lymphocytes are agranulocytes and lack the specific
granules characteristic of granulocytes.
Lymphocytes circulating in blood generally range in size
from 6 to 15 μm in diameter and are sometimes classified
arbitrarily as small, medium, and large.
(a) The most numerous small lymphocytes shown here
are slightly larger than the neighboring erythrocytes and
have only a thin rim of cytoplasm surrounding the spherical
nucleus.
(b) Medium lymphocytes are distinctly larger than
erythrocytes.
(c) Large lymphocytes, much larger than erythrocytes,
may represent activated cells that have returned
to the circulation.
39. Maturation the platelets
• The membrane-enclosed cell fragments called platelets
or thrombocytes originate in the red bone marrow by
dissociating from mature megakaryocytes (Gr. megas,
big + karyon, nucleus, + kytos),
40. • (a) Megakaryoblasts (Mb) are very large, fairly rare cells in bone marrow, with very
basophilic cytoplasm.
• (b) Megakaryoblasts undergo endomitosis (DNA replication without intervening cell
divisions), becoming polyploid as they differentiate into megakaryocytes (M). These
cells are even larger but with cytoplasm that is less intensely basophilic.
• (c) Micrograph of sectioned bone marrow in which a megakaryocyte (M) is shown
near sinusoids (S).
• Megakaryocytes produce all the characteristic components of platelets
(membrane vesicles, specific granules, marginal microtubule bundles, etc) and in a
complex
• process extend many long, branching pseudopodia-like projections called
proplatelets, from the ends of which platelets are pinched off almost fully formed.
41. Platelets
• In a blood smear, platelets (arrows) are often found
as aggregates. Individually they show a lightly
stained hyalomere region surrounding a more
darkly stained central granulomere containing
membrane-enclosed granules.
• The role of platelets is preventing blood loss
(hemorrhage)
42. Clinical correlate
• Aspirin and other nonsteroidal anti-inflammatory
agents have an inhibitory effect on platelet function
and blood coagulation because they block the local
prostaglandin synthesis that is needed for platelet
aggregation, contraction, and exocytosis at sites of
injury.
