In erythropoiesis, the sequence of erythrocyte formation is chronologically described in which option?
a- Stem cells, erythroblast, reticulocyte, erythrocytes.
b- Stem cells, reticulocyte, erythroblast, erythrocytes.
c- Erythroblast, stem cells, reticulocyte, erythrocytes.
d- Erythroblast, reticulocyte, stem cells, erythrocytes.
Answer A.
Rationale: Stem cells – erythroblast- reticulocyte – erythrocytes. Erythropoietin is the hormone that stimulates red blood cell production in the red marrow.
Mature red blood cells are formed from stem cells in the bone marrow. With the presence of erythropoietin, red cell pathway starts to form proerythroblast from stem cells.
At this point the cell still contains nucleus.
However, as the development progresses the nucleus becomes smaller and the cytoplasm becomes basophilic due to the presence of ribosome, thus the cell is now called basophilic erythroblast. As the cell becomes older it also becomes smaller and eventually when it begins to produce hemoglobin it is now termed as polychromatic erythroblast.
Later on the cytoplasm will become more eosinophilic and the cell is now called orthochromatic erythroblast, which will then extrude its nucleus as the cells slowly fill with hemoglobin before entering the circulation as reticulocytes. Reticulocytes will mature to form the anucleated red blood cells.
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Hematology