Erythropoiesis

This composite image shows the different stages of erythropoiesis. The proerythroblast is slightly smaller than the blast cell and appears more basophilic. It loses its nucleolus and becomes a basophilic erythroblast, which is much smaller than the original blast and has an intensely basophilic cytoplasm due to the accumulation of ribosomes. The basophilic erythroblast develops into a polychromatic erythroblast. This cell has a gray-green cytoplasm that results from the accumulation of hemoglobin. In an orthochromatic erythroblast, the nucleus has shrunk and become darker and the growing concentration of hemoglobin turns the cytoplasm pink. Finally, the nucleus is extruded via an asymmetric division of the cytoplasm, resulting in the formation of a reticulocyte. This cell is characterized by a bluish hue due to ribosomes remaining in its cytoplasm. Eventually, the loss of all organelles results in the transition from reticulocyte to mature erythrocyte.