Hemopoiesis (Haematopoiesis)

• Hemopoiesis (Haematopoiesis) is the process by which blood cells are produced in the body, primarily occurring in the bone marrow.
• Hematopoietic stem cells (HSCs) differentiate into various blood cell types, including erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets).

Erythropoiesis

• Production of erythrocytes (red blood cells) responsible for oxygen transport.

• Process:

• Begins with HSCs differentiating into proerythroblasts.
• Under the influence of erythropoietin (EPO), proerythroblasts develop through several stages:
• Proerythroblast → Basophilic erythroblast → Polychromatophilic erythroblast → Orthochromatophilic erythroblast → Reticulocyte.
• Reticulocytes enter the bloodstream and mature into erythrocytes.

Leukopoiesis in Hemopoiesis (Haematopoiesis)

• Production of leukocytes (white blood cells) for immune defense.

• Process:

• HSCs differentiate into myeloid or lymphoid progenitor cells.
• Myeloid progenitor cells develop into granulocytes (neutrophils, eosinophils, basophils) and monocytes.
• Lymphoid progenitor cells develop into B and T lymphocytes and natural killer (NK) cells.
• Regulated by cytokines and growth factors like GM-CSF, G-CSF, and interleukins.

Thrombopoiesis

• Production of thrombocytes (platelets) for blood clotting.

• Process:

• HSCs differentiate into megakaryocyte progenitor cells.
• Under the influence of thrombopoietin (TPO), these progenitors mature into megakaryocytes.
• Megakaryocytes extend proplatelets into bone marrow blood vessels, which fragment into platelets released into the bloodstream.

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