HAEMOPOIESIS
Mohammed Basil .p.a.
Second Year BSc MLT
Archana madam & Rijo jeckeb joseph sir
(Pathology dept.)
Erythropoiesis or haemopoiesis is the physiological
process of production of RBC. It is mostly place in
the bone marrow but it depend upon the stage of
life.

Life stages
 Granulocytes
 Erythrocytes
 Platelets
 Lymphocytes

Derived from Stem cells
 .01% - .05% of the marrow cells

Stem cells
 Self renewal
 Plasticity

Progenitor cells
 Developmentally-restricted cells

Mature cells
 Mature cell production takes place from the more
developmentally-restricted progenitors



Yolk sac
(1-3 month)
Liver and spleen
(3-6 month)
Bone marrow
(After birth)

Self-renewal
 Normally in G0 phase of cell cycle
 The capacity for self-reproduction is vastly in excess of
that required to maintain cell production for normal
lifetime
 As cells increase in number they differentiate as well

Multipotentiality
 Capacity to generate cells of all the
lymphohaemopoietic lineages


Encompasses from immediate progeny of stem
cells to cells committed to one differentiation
lineage
Progenitor cells become progressively more
restricted in their differentiation and
proliferation capacity
 Late progenitor cells eventually restricted to one
lineage
Controlled cell
death

Controlled cell
production
There should be a balance between cell
production and cell death except at the times of
requirement

GM-CSF
 Granulocyte-Macrophage colony stimulating factor

M-CSF
 Macrophage colony stimulating factor

Erythropoietin
 Erythropoiesis stimulating hormone
(These factors have the capacity to stimulate the proliferation of their
target progenitor cells when used as a sole source of stimulation)

Thrombopoietin
 Stimulates megakaryopoiesis

Cytokines









IL 1 (Interleukin 1)
IL 3
IL 4
IL 5
IL 6
IL 9
IL 11
TGF-β
SCF (Stem cell factor, also known as kit-ligand)
Cytokines have no (e.g IL-1) or little (SCF) capacity to stimulate cell
proliferation on their own, but are able to synergise with other
cytokines to recruit nine cells into proliferation
Local environmental control
Stromal cell mediated Haemopoiesis
Apoptosis
Haemopoietic
growth factors (Humoral regulation)

Regulated physiological cell death
 Homeostasis
 Morphological evidence
 Enzymatic digestion of DNA and cell disintegration
 Caspases
 Endonuclease

Two major pathway of activation of caspases
 Membrane signalling
 Cytochrome c release

Lifespan – 120 days

Non nucleated

Biconcave disc


Production regulated by
Epo
Needs Fe, B12, folate &
other elements for
development


Granulocytes

Neutrophils

Eosinophils

Basophils
Only mature cells
are present in
peripheral blood
E
N
B

Neutrophil
2-5 lobe nucleus
 Primary or secondary
granules

 Pink (azurophilic granules)
 Grey-blue granules

Life 10 hours

Eosinophils




Coarser & more deeply red staining granules
Rarely more than two lobes of nucleus
Special role in allergy, inflamation & parasite
infection
Basophils




Occasionally seen
Dark cytoplasmic granules
Role in hypersensitivity response
Give rise to mast cells




Larger than lymphocyte
Oval or indented
nucleus
Monocytes >>>>to
macrophage
Specific function
depends on the tissue
type


Immunologically competent cells
Primary lymphoid organs
 Bone marrow
 Thymus

Secondary lymphoid organs
 Lymph nodes
 Spleen
 Lymphoid tissues

Lymphocytes
 B and T lymphocytes
 NK killer cells





Platelet play a major
role in primary
hemostasis
Life span 7-10 days
Production,
fragmentation of
cytoplasm
Megakaryocytes
undergoes
endomitotic division
1/3 in spleen




Normal haemopoiesis is necessary for the
survival
It is under the control of multiple factors
Normal bone marrow environment is
necessary for normal haemopoiesis
Decreased production results in cytopenias