Haemopoiesis Flashcards
What are the four types of haemopoiesis?
- erythropoiesis
- thrombopoiesis
- lymphopoiesis
- myelopoiesis/granulopoiesis
How are red cells measured and how long do they last?
x10^12/l
120 days
How are neutrophils measured and how long do they last?
x10^9/l
7-8 hours
How are platelets measured and how long do they last?
x10^9/l
7-10 days
What does ‘blast’ mean?
Nucleated precursor cell
What is a megakaryocyte?
Platelet precursor
What is a myelocyte?
Nucleated precursor between neutrophils and blasts
Describe haemopoietic stem cells
Progenitor with the ability to self-renew
Asymmetrical division allows stem cell preservation and differentiation
Define maturation
Acquisition of functional properties
What can myeloid mean?
Marrow
Non-lymphoid lineage
Granulocytic portion of the marrow
Where does marrow originate embryonically?
Mesoderm
When can progenitors be detected?
As early as week 5
Where is the first place to produce stem cells?
Yolk sac
When does yolk sac activity stop?
Week 10
When do the marrow and liver start to produce stem cells?
Liver - week 6
Bone marrow - week 16
What is meant by cellularity?
Percentage of active cells in marrow
Red marrow
Yellow marrow - fatty and inactive increases with age
Where are bone marrow biopsies taken?
Adult - posterior iliac crest
Children - tibial marrow cavity
Name the three compartments of the bone marrow
Cellular
Connective tissue matrix
Vascular elements
What non-haemopoieotic cells are found in the marrow?
Adipocytes, fibroblasts, osteoclasts, osteoblasts
Describe the vasculature of the marrow
Nutrient artery and periosteal network
Sinuses and sinusoids
How are sinusoids different to capillaries?
Larger and have a discontinuous basement membrane
Describe the structure of sinusoids
Endothelial cells with a discontinuous BM, gaps in between cells and adventitial cells which can alter the space
What do the sinusoids create?
Pores/fentrations that allow mature cells to migrate through and enter the circulation
Describe sinusoid response to blood loss
Dilatation to increase blood flow
Which direction do neutrophils travel?
Down the chemokine gradient - towards the sinusoid
Describe the relationship between megakaryocyte and sinusoidal blood vessels
Megakaryocytes extend long branching processes - pro platelets into the sinusoidal blood vessels
State the three components of regulation of erythropoiesis
Intrinsic properties of cells
Signals from immediate surroundings of periphery
Specific anatomical area ‘niche’ for optimal developmental signals
Give examples of marrow regulation
Renal erythropoietin
Erythroid islands ‘nurse’ macrophages, growth factors provided
Neutrophil precursor maturation regulated by GCSF
Thrombopoietin from the liver regulates growth and development of megakaryocytic
What is GCSF?
Granulocyte colony stimulating factor
How can marrow be investigated?
Blood count Cell inidices Morphology Bone marrow examination Immunophenotyping Cytochemistry
Describe immunophenotyping
Study of antigen expression using specific antibodies indicating lineage/stage of development
