Question

In embryonic stage, RBCs develop in
A. Liver and kidney
B. Liver and spleen
C. Spleen and kidney
D. Liver and pancreas

Answer 1

Hint: RBCs are Red blood cells found in the human blood. Erythropoiesis is the process of producing red blood cells or erythrocytes which is developed from erythropoietic stem cells and mature into the red blood cells. RBCs contain haemoglobin and are non-nucleated.

Complete answer: Haemopoiesis: It is the development of blood cells that are RBCs, WBCs, and platelets. The term hematopoiesis includes:
-Erythropoiesis: It means the development of RBCs.
-Leucopoiesis: It means the development of WBCs.
-Megakaryocytopoiesis: It is the development of platelets.
During Intrauterine life, erythropoiesis occurs in three stages:
1. Mesoblastic stage: In early embryos up to 3 months of foetal life, RBCs are formed from the mesoderm of the yolk sac.
2. Hepatic Stage: After 3 months of foetal life, the liver and spleen are the site of blood formation.
3. Myeloid Stage: In the middle of foetal life, erythropoiesis occurs in the bone marrow. Hepatic and myeloid stages are extravascular erythropoiesis.
In children, erythropoiesis occurs in all bones with red marrow mainly, liver, and spleen.
Adults, after 18-20 years of age from red bone marrow this includes:
1. Ends of long bones.
2. Skull
3. Ribs
4. Sternum
5. Pelvis
In the early foetus, erythropoiesis takes place in the mesoderm cells of the yolk sac. By the third or fourth month, erythropoiesis moves to the liver. After seven months, erythropoiesis occurs in the bone marrow.
So, the correct option is option B. Liver and spleen.

Note: The stages of erythropoiesis are:
1. Hemocytoblast
2. Proerythroblast
3. Early, intermediate and late normoblast
4. Reticulocyte
5. Erythrocyte
Disorder related to the deficiency of RBC or haemoglobin: Anemia is the clinical condition characterized by a reduction in the number of RBCs less than 4 million or their content of haemoglobin is less than 12g or both.