haemopoiesis. mohammed basil.p.a. second year bsc mlt
TRANSCRIPT
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