Notes / Presentation on Erythropoiesis Process & Stages in
Human Body for Medical Biology Students in word/ .pdf /. Ppt Format
ERYTHROPOIESIS
DEFINITION
Erythropoiesis
is the process by which the origin, development and maturation of erythrocytes
occur. Hemopoiesis is the process which includes origin, development and
maturation of all the blood cells.
SITE OF ERYTHROPOIESIS
IN
FETAL LIFE
During
embryonic life, the erythropoiesis occurs in three stages.
- Mesoblastic
stage: During the first two months of
intrauterine life, the primitive red blood cells are produced from
mesenchyme of yolk sac.
- Hepatic
stage: From third month of intrauterine
life, liver is the main organ that produces red blood cells. Some
erythrocytes are also produced from spleen and lymphoid organs.
- Myeloid
stage: During the last three months of
intra uterine life, the red blood cells are produced red bone marrow and
liver.
POSTNATAL
LIFE AND IN ADULTS
In
newborn babies, growing children and adults, the blood cells are produced only
from the red bone marrow.
1. Up to the age of 5 to 6 years: The red blood
cell produced in red bone marrow of all
bones.
2. From 6th year up to 20th year: The red blood
cell produced by red bone marrow of long bones and the membranous (flat) bones.
3. After the age of 20 years: The red blood
cells produced from all membranous bones like vertebra, sternum, ribs, scapula,
iliac bones and skull bones and from the ends of long bones. After 20 yea age,
the shaft of the long bones becomes yellow bone marrow because of fat
deposition and looses the erythropoietic function. During disorders of bone
,the red blood cells are produced in the spleen.
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