QS Study

Erythropoiesis is the process of formation of erythrocyte under normal physiological condition. It is the procedure which produces red blood cells. It is stimulated by decreased oxygen in circulation, which is detected by the kidneys, which then secrete the hormone erythropoietin.


(a) On the basis of predominant cell in Bone marrow – Erythrocytes are by far the predominant cell type in the blood smear. They are anucleate, non-granulated, eosinophilic cells that are uniform in shape and size. These cells contain hemoglobin and are responsible for the transport and delivery of oxygen. Erythrocytes have a lifespan of 120 days.

(i) Normoblastic erythropoiesis

(ii) Micronormoblatic erythropoiesis

(iii)Megaloblastic erythropoiesis

(iv) Macronormobalastic erythropoiesis.

(b) On the basis of stage of life: In fetal life, the erythropoiesis occurs in three stages:

  • Mesoblastic stage- for the duration of the first two months of intrauterine life, the RBCs are produced from mesenchyme of yolk sac.
  • Hepatic stage- as of the third month of intrauterine life, the liver is the key organ that produces RBCs.
  • Myeloid stage- all through the last three months of intrauterine life, the RBCs are produced from red bone marrow and liver.