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L13 Erythropoiesis and Haemoglobin Production
The erythron: The total mass of circulating RBCs and the RBC-forming tissues from which they are derived
Red cell differentiation
 Haematopoietic stem cell 

Erythroid development
 Early stages of differentiation can only be indentified by cell markers (immunophenotyping)
 Late differentiation can be seen by morphology
o Pro erythroblasts/pro normoblasts
o Early erythroblasts/ basophilic normoblasts
o Late erythroblasts/ orthochromatic normoblasts
o Reticulocytes
o RBCs
Erythroid maturation
 RBC start to produce haemoglobin
 RBC loses nucleus
 Proliferation and differentiation processes occurring within the erythroid niche
Erythroid islands in bone marrow
 Blood cells from in groups around macrophages
 As the RBCs loses their nuclei the macrophages eat them
RBC structure
 Biconcave bag of haemoglobin
 Normoblasts extrude nucleus
 Autography/mitophgy in reticulocytes – no mitochondria
 Therefore sensitive to oxidative damage
 Not many organelles = very flexible
 Very flexible because of Ankyrin and spectrin proteins attached membrane
...

 Can activate or repress genes
 GATA switch
o GATA2 can drive expression of the GATA2 gene
o When GATA1 expression is strong it can repress expression of GATA2
 GATA-2 mutations are a target for human haematological disorders
Shifts in site of haemaptopoeisis during development
1
...
1st hepatic colonisation
3
...
2nd hepatic colonisation
5
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