Erythropoiesis (RBC production)

Erythropoiesis is the production of RBCs . This ppt contains general and concised information about RBC production in prenatal, neonatal and in young and adult life.

1. Erythropoiesis (RBC production) M. FARAN YOUSAF 2018-DVMN-038 Group B (b) (Other members are 036,037,039,040 ) Presented to : Dr. M. Sulman Ali Taseer

2. Outline: Introduction Sites of production Mechanism of production Stages of differentiation Regulation of RBC production References

3. Introduction: Hemopoiesis : Production of Blood ( Hemo: Blood , Poiesis : Production) It includes : Erythropoiesis : Erythrocyte production Leucopoiesis : Leukocyte production Thrombopoiesis : Thrombocyte (platelets) production etc…

4. Erythropoiesis: It is the process of development, differentiation and maturation of RBCs from primitive stem cells. Two theories of blood production are given : Monophyletic : There is a common parent cell of all formed elements of blood. Polyphyletic : Suggests different group of stem cells gives rise to different blood cells. .

5. Sites for production: In the early weeks of embryonic life, primitive, nucleated RBCs are produced in the yolk sac (mesoblastic stage). During the middle trimester of gestation, the liver is the main organ for production of RBCs, but reasonable numbers are also produced in the spleen and lymph nodes.(Hepatic stage) During the last month or so of gestation and after birth, RBCs are produced exclusively in the bone marrow . (Myeloid stage)

6. Sites for RBC production: In Children Active bone marrow is present throughout the axial skeleton and the long bones like the tibia and femur etc. In adults(after 20 yrs ) The accumulation of fat in the bone marrow makes them inactive for the production of RBCs (Yellow bone marrow) and only few bones of axial skeleton and ends of femur and tibia are able to produce erythrocytes.

7. Mechanism: All blood cells start their lives in bone marrow from pluripotential hematopoietic stem cell (PHSC) PHSC replicates and maintains its small proportion in the bone marrow. PHSC reproduces and forms colony forming units also known as committed stem cells e.g. CFU-E , CFU-GM These colony forming units form mature cells.

8. Stages of differentiation: CFU-E forms a large no. of proerythroblasts. Proerythroblasts divide and produce a large no. of RBCs. First gen. of these are called basophil erythrocytes because they dye with basic stains and have a little Hb. In the succeeding generations the cells become filled with hemoglobin to a concentration of about 34 percent, the nucleus condenses to a small size, and its final remnant is absorbed or extruded from the cell. The endoplasmic reticulum is also reabsorbed. The cell at this stage is called a reticulocyte. Reticulocytes move from bone marrow to blood through diapedesis and after 1-2 days it becomes a mature erythrocyte.

9. Regulation of RBC production: When tissue oxygenation decreases due to several factors like Low blood volume, Anemia, Low hemoglobin, Poor blood flow, Pulmonary disease etc. Erythropoietin subsequently decreases. Kidney produces Erythropoietin which stimulates the production of proerythroblasts , thus speeding up the RBC production.

10. References: Guyton and Hall Textbook of Medical Physiology, 13th Edition Physiology of domestic animals- Sajjastad . Google Slideshare.net

11. Thank You. Any Questions?