The process of formation of blood cells i.e. RBC’S, WBC’S and platelets is called as haematopoiesis

1. Sahyadri science college, Shimogga.
Topic On
HEMATOPOEISIS
INDUDHAR S O
1st M,Sc
Biotechnology
Sahyadri science
college,
Shivamogga.

2. CONTENTS
 Site of haemopoiesis
 Haemopoietic stem and progenitor cells
 Bone marrow stroma
 The regulation of haemopoiesis
 Haemopoietic growth factors
 Conclusion
 References
 Introdution

3. INTRODUCTION
• The process of formation of blood cells i.e. RBC’S,
WBC’S and platelets is called as haematopoiesis
and the sites where it occurs are known as
hemopoietic tissues or organs (bone marrow,
liver, spleen)
• Cells responsible to do function of hemopoiesis
are first seen in yolk sac of embryo in third week
of embryonic development and these cells are
known as hematopoietic stem cells
• Approximately 1010-1011 new blood cells are
produced daily in the human body

4. Site of haemopoiesis
• In the first few weeks of gestation the yolk sac is
the main site of haemopoiesis, haemopoiesis
derives from a population of stem cells
• These common precursor of endothelial and
haemopoietic cells are believed to seed the liver,
spleen and bone marrow and from 6 weeks until
6–7 months .
• The liver & spleen are the major haemopoietic
organs and continue to produce blood cells until
about 2 weeks after birth.

5. • bone marrow
• In normal childhood and adult life the marrow is the
only source of new blood cells.
• Sites of haemopoiesis.
• Fetus 0–2 months (yolk sac)
• 2–7 months (liver, spleen)
• 5–9 months (bone marrow)
• Infants Bone marrow (practically all bones)
• Adults Vertebrae, ribs, sternum, skull, sacrum
• and pelvis, proximal ends of femur

6. Haemopoietic stem and progenitor
cells
• Haemopoiesis starts with a pluripotential stem
cell that can give rise to the separate cell
lineages.
• Cell differentiation occurs from the stem cell
via the committed haemopoietic progenitors
• Very early progenitors are assayed by culture
on bone marrow stroma as long-term culture
initiating cells whereas late progenitors are
generally assayed in semi-solid media.

8. • Example is the earliest detectable mixed
myeloid precursor which gives rise to
granulocytes, erythrocytes, monocytes and
megakaryocytes and is termed CFU (colony-
forming unit)-GEMM
• The bone marrow is also the primary site of
origin of lymphocytes which differentiate
from a common lymphoid precursor.

9. Bone marrow stroma
• The bone marrow forms a suitable
environment for stem cell survival, growth and
development.
• It is composed of stromal cells and a
microvascular network, The stromal cells
include adipocytes, fibroblasts, endothelial
cells and macrophages
• they secrete extracellular molecules such as
collagen,glycoproteins

10. • Stem cells are able to traffic around the body
and are found in peripheral blood in low
numbers.
• mobilization:
• cells must cross the blood vessel endothelium
and this process is called mobilization

11. Maturing and mature cells
• The maturing and mature haemopoietic cells are
recognizable on stained smears of blood
• During maturation, the cells maintain some
capacity for division that can influence the blood
count ,the capacity for cell division is lost because
of expulsion of the nucleus (red
cells),fragmentation (platelets)
• The end-products of haemopoietic cell
development are cells that are highly specialized
for their different functions in the body.

12. The regulation of haemopoiesis
• They express low levels of transcription factors
that may commit them to discrete cell
lineages.
• For instance, PU.1 commits cells to the
myeloid lineage whereas GATA-1 has an
essential role in erythropoietic and
megakaryocytic differentiation

13. Haemopoietic growth factors
• The haemopoietic growth factors are
glycoprotein hormones that regulate the
proliferation and differentiation of
haemopoietic progenitor cells and the
function of mature blood cells.
• The growth factors may cause cell
proliferation but can also stimulate
differentiation, maturation, prevent apoptosis
and affect the function of mature cells

14. • Stromal cells are the major source of growth
factors except for erythropoietin,90% of which
is synthesized in the kidney and
thrombopoietin, made largely in the liver.

16. MYELOID LINEAGE:
• The term “myeloid” means either “pertaining to
bone marrow” or “resembling bone marrow”
• Cells of myeloid lineage develop during the process
of myelopoisis & include granulocytes
monocytes,megakaryocytes,dendritic cells,
erythrocytes & platelets develop from myeloid
progenitor cells

17. MONOCYTES
• Monocytes are the type of WBCs. They are the
largest of all leukocytes.
• They are the part of innate immune system of
vertebrates including all mammals, birds, rptiles
and fishes.
• They are amoeboid in shape, having agranulated
cytoplasm, they have unilobar nuclei, which
makes them one of the types of mononuclear
leucocytes.
• Monocytes constitute 2% to 10% of all the
leucocytes.

18. MACROPHAGES
• Macrophages are the type of
WBC , that engulfs and digests
cellular debries, foreign
substances, microbes, cancer
cells and anything that does
not have the type of protein
specific to the surace of
healthy body cells on its
surface in a process called
phagocytosis
• After the monocytes become
macrophages most
importently the phagocytic
property of the cell increased.

19. NEUTROPHILS
• Neutrophil granulocytes (also known as neutrophils or occasionally neutrocytes) are
the most abundant type of granulocytes and the most abundant (40% to 75%) type
of white blood cells in most mammals. They form an essential part of the innate
immune system.
• They are short-lived and highly motile, or mobile, as they can enter parts of tissue
where other cells/molecules wouldn't be able to enter otherwise.
• During the beginning (acute) phase of inflammation, particularly as a result of
bacterial infection, environmental exposure, and some cancers, neutrophils are one of
the first-responders of inflammatory cells to migrate towards the site of inflammation.

20. EOSINOPHILS
• Eosinophill granulocytes, usually called eosinophils are eosinophiles, a
variety of WBC and one of the immune system components
responsible for combating multicellular paracytes and crtain infection
in vertebrates.
• Their nucleus has only two lobes, almost all of the cytoplasm appears
filled with the specific granules of the eosinophills which are rich in
hydrolyti enzymes
• They are also called as acidophills, as they have greater affinity for
acidic dyes, such as eoisin hence they are termed as eoisinophills

21. BASOPHILLS
• Basophill granulocytes, mostly reffered to as basophills are the
least common of the granulocytes, representing about 0.01%
to 0.3% of circulating WBC
• These cells are named so, because of their cytoplasm
containing granules that stains with basic dye.
• The basophils granules are belived to contain heparin,
histamine, serotonin, platelet activating factor and other
vasoactive amines

22. PLATELETS
• Platelets, also called thrombocytes are a component of blood
whose function (along with the coagulation factors) is to stop
bleeding by clumping and clotting blood vessel injuries.
• Platelets have no cell nucleus: they are fragments
of cytoplasm that are derived from the megakaryocytes of
the bone marrow, and then enter the circulation

23. LYMPHOID LINEAGE
• Lymphocytes constitute 20%–40% of the body’s white blood
cells and 99% of the cells in the lymph.
• These lymphocytes continually circulate in the blood and
lymph and are capable of migrating into the tissue spaces and
lymphoid organs,
• Two morphological distinct lymphocytes can be observed in
the blood the first type is the small agranular lyphocyte
having high nuclear-to-cytoplasm ratio.these lymphocytes are
further divided into two types they are T and B lymphocytes
• The second type is a large cell, which is granulated, and
posses low nuclear-to-cytoplasmic ratio. They are called as
large granulated lymphocytes. Lymphocytes normally possess
specific receptors for antigens and thus mediate specific
immunity.

24. T-Lymphocytes
• T cells(also known as thymocytes cells) or T lymphocytes are the type of
lymphocytes that play a central role in cell mediated immunity .
• The T lymphocytes are found in the bone marrow as pre T lymphocytes.
Then they enter the thymus to become matured T lymphocytes. Most of
the circulating lymphocytes are T lymphocytes and contribute to about
80% of the lymphocyte population.
• The T cells play two important function-effector and regulatory.
• The effector function includes cytolysis of cell infected with microbes and
tumour cells and lymphokine production. The regulatory functions are
either to increse or to supress other lymphocytes and accessory cells.
• T cells are two types:
 T helper cells
 T cytotoxic cells

25. B-Lymphocytes
• They are the type of WBCs of the lymphocyte subtype.
• Bone marrow is its major site of maturation
• They are very important in antibody-mediated
immunity as they secrete specific immunoglobulins in
response to antigenic stimulus.
• The B cells are of two subunits.
• T-cell-independent cell: which do not require the help
of T h cells for the production of immunoglobulins.
• T-cell-dependent cell: which require the help of T h
cells for the production of immunoglobulins.

26. NATURAL KILLER CELLS
• NK cells were subsequently shown to play an
important role in host defense both against
tumor cells and against cells infected with
some, though not all, viruses.
• These cells, which constitute 5%–10% of
lymphocytes in human peripheral blood

27. REFERENCES
• Kuby, immunology.
• Ian R. Tizard, Immunology, An introduction,
Thomson Asia Pte-Ltd Singapore.
• KR Joshi/N.O Osama, Immunology , agrobios
(India) publication.
• WEBSITES
https://en.m.wikipedia.org/wiki/Haematopoiesis