SEMINAR

HAEMOPOIESIS

SUBMITTED BY

Mohammed Basil .p.a.Second Year BSc MLT

SUBMITTED TOArchana madam & Rijo jeckeb joseph sir(Pathology dept.)

Haemopoiesis

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.

Introduction

Life stages

Granulocytes Erythrocytes Platelets Lymphocytes

Derived from Stem cells .01% - .05% of the marrow cells

Introduction

Stem cells Self renewal Plasticity

Progenitor cells Developmentally-restricted cells

Mature cells Mature cell production takes place from the more

developmentally-restricted progenitors

Cell hierarchy (Haemopoiesis schematic representation)

Sites of Haemopoiesis

Yolk sac (1-3 month) Liver and spleen (3-6 month) Bone marrow

(After birth)

Stem cells

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

Interaction of stromal cells, growth factors and haemopoietic cells

Progenitor cells

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

Regulation of Haemopoiesis

There should be a balance between cell production and cell death except at the times of requirement

Controlled cell death

Controlled cell production

Local and Humoral regulation of Haemopoiesis

Haemopoietic growth factors

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

Haemopoietic growth factors

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

Role of growth factors in normal haemopoiesis

Regulation of Haemopoiesis

Apoptosis

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

Mechanism; apoptosis

Erythropoiesis and erythrocytes

Lifespan – 120 days

Non nucleated

Biconcave disc

Production regulated by Epo

Needs Fe, B12, folate & other elements for development

Development of mature red cells

Granulopoiesis

Granulocytes Neutrophils

Eosinophils

Basophils

Only mature cells are present in peripheral blood

E

N

B

Granulopoiesis 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

Granulopoiesis

Monocytes

Larger than lymphocyte

Oval or indented nucleus

Monocytes >>>>to macrophage

Specific function depends on the tissue type

Lymphopoiesis

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

Thrombopoiesis

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

Summary

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

Thank you