cytological differentiation

Last reviewed 01/2018

The differentiation of erythrocytes takes place over about 6 days within the extravascular cords of red bone marrow.

The stages involved include sequentially:

  • primitive haemopoietic stem cell
  • uncommited stem cell
  • proerythroblast:
    • relatively large cell and nucleus
    • mildly basophilic staining
  • basophilic erythroblast: intensely basophilic staining due to large numbers of ribosomes producing haemoglobin
  • polychromatophilic erythroblast:
    • smaller cell and nucleus
    • increasing amounts of haemoglobin, eosinophilic in nature, result in dual staining
  • normoblast:
    • small nucleus
    • large amounts of eosinophilic cytoplasm due to haemoglobin
  • reticulocyte:
    • nucleus is extruded
    • passes into blood to mature into final erythrocyte

Differentiation accompanies up to 4 mitotic divisions yielding up to 16 erythrocytes for each stem cell.