Erythropoiesis

Erythropoiesis is the development of mature red blood cells (erythrocytes). Like all blood cells, erythroid cells begin as pluripotential stem cells. The first cell that is recognizable as specifically leading down the red cell pathway is the proerythroblast . As development progresses, the nucleus becomes somewhat smaller and the cytoplasm becomes more basophilic, due to the presence of ribosomes. In this stage the cell is called a basophilic erythroblast . The cell will continue to become smaller throughout development. As the cell begins to produce hemoglobin, the cytoplasm attracts both basic and eosin stains, and is called a polychromatophilic erythroblast . The cytoplasm eventually becomes more eosinophilic, and the cell is called an orthochromatic erythroblast . This orthochromatic erythroblast will then extrude its nucleus and enter the circulation as a reticulocyte . Reticulocytes are so named because these cells contain reticular networks of polyribosomes. As reticulocytes loose their polyribosomes they become mature red blood cells.

Examples of the developing cells are shown below. Mature erythrocytes are visible in most pictures. A pure field of mature erythrocytes can also be seen by clicking here .

 
stem cell late stem cell

proerthroblast
(pronormoblast)

basophilic erythroblast
       
polychromatophilic erythroblast

orthocromatophilic erythroblast
(Normoblast)

orthochromatic erythroblast extruding its nucleus

reticulocyte
(polychromatophilic erthrocyte)

Return to Hematopathology ; Department of Pathology ; or Tulane University Medical Center .
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by Robert McLay