Erythropoiesis:- During intrauterine life:- 3 stage
1). Mesoblastic:- In early embryos up to three months of fetal life RBCs are Formed the mesoderm of the yolk sac.
2). Hepatic stage:- After three months of Foetal life liver and spleen are the site of blood formation.
3. Myeloid stage:- From the middle of foetal life RBCs formation occurs in the bone marrow.
In children:- In children erythropoiesis occurs in -
1). All bones with red marrow.
2). Liver
3). Spleen
In Adults:- (18-20 years) from red marrow included-
1). Ends of long bone like femur and humerus.
2). Skull
3). Vertebrae
4). Ribs
5). Sternum
6). Pelvis
Stages of Erythropoiesis:-
Haemocytoblast ↓
↓ ↓
Proerythroblast ↓
↓ ↓
Normoblast ↓
↓ 7 Days
Early Normoblast ↑
↓ ↑
Intermediate Normoblast ↑
↓ ↑
late Normoblast ↑
↓
Reticulocyte ↓
↓ 2 Days
Erythrocyte ↑
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