red blood cell - erythropoiesis
DESCRIPTION
For MBBS studentsTRANSCRIPT
RED BLOOD CELL- IIERYTHROPOIESIS
Dr. Elizabeth JProf & HOD,AIMS &RC, Bangalore
04/09/14
STAGES / FACTORS REGULATING
Scheme
Definition Theories of erythropoiesis Sites of erythropoiesis Stages of erythropoiesis Description of blast cells Reticulocyte Mature Red Cell Factors affecting Erythropoiesis Erythropoietin Absorption of Vitamin B12
DEVELOPMENTMULTIPLICATIONMATURATIONDIFFERENTIATION
DEFINITION
STOCHASTIC THEORY
HAEMPOIETIC INDUCTIVE MICROENVIRONMENT
HUMORAL FACTORS
“Theories that address the process of commitment of stem cell progeny”
3 stages of erythropoiesis during intrauterine life
o mesoblastic (1st 3 months)o hepatic (after 3 months)o myeloid (3rd trimester)
Site of Erythropoiesis
PHSC Pluripotent Hemopoietic stem cell
BFU-E Burst Forming Unit Erythrocyte
CFU-E Colony Forming Unit Erythrocyte
PROERYTHROBLAST
BASOPHILIC ERYTHROBLAST
POLYCHROMATOPHILIC ERYTHROBLAST
ORTHOCHROMATIC ERYTHROBLAST
RETICULOCYTE
ERYTHROCYTEERYTHROCYTE
E
R
Y
T
H
R
O
P
O
I
E
S
I
S
GM CSF erythro IL-1,IL-6,IL-3
GM CSF erythro
ERYTHROPOIESIS
15-20µm- basophilic cytoplasm, nucleus with nucleoli.
14-17µm-mitosis, basophilic cytoplasm, nucleoli disappears.
10-15µm- ’POLYCHROMASIA’Hb appears, nucleus
condenses.
7-10µm- PYKNOTIC Nucleus.Extrusion, Hb is maximum.
7.3µm- Reticulum of basophilic material in the cytoplasm.
7.2µm- Mature red cell with Hb.
BFU-E CFU-E
STAGES OF ERYTHROPOIESIS
Proerythroblast• Earliest erythroid element
• Basophilic cytoplasm with a
perinuclear halo
• Cytoplasm bulges to form
“Ear shaped” process
• Nuclear chromatin is not
homogenous & Nucleolus is seen
Basophilic erythroblast/Early normoblast
• Smaller than Proerythroblast
• Nuclear chromatin shows
sharp contrast between light
& dark areas
• Cytoplasm is basophilic
reflecting protein & RNA contents
Polychromatophilic erythroblast/Intermediate normoblast
• Polychromasia means
having many colors
• Nucleus mature & condensed
• Cytoplasm has a gray hue
derived from Hb (Hemoglobin)
Orthochromatic erythroblast/Late normoblast
• Acidophilic erythroblast which is
the last precursor with a nucleus
• Nucleus is compact & situated
near the membrane
• Cytoplasm is like mature red cell,
reflecting a high Hb content
Reticulocyte
-Young erythrocytes with granular or reticular filamentous structures
-Makes up 0.5-2% of all erythrocytes
-Vital staining required to make this visible.
-Reticulocytosis seen following hemolysis or acute blood loss
Reticulocyte as seen under the SEM
Mature non-nucleated erythrocyte
• Reddish, circular, biconcave cells
• 7-8 µ
• No visible internal structure
• High Hb content
• Bright at centre due to biconcave
shape
Erythrocyte as seen under the SEM
Erythropoietin (EPO): major humoral
regulator of erythropoiesis Interleukins, IL3,IL6 & IL1 Iron VitaminB12(Cyanocobalamine)+Folic Acid +
Vitamin C(Ascorbic Acid) Intrinsic factor for absorption of B12
FACTORS AFFECTING ERYTHROPOIESIS
PHSC
PROERYTHROBLAST
ERYTHROCYTE
TISSUE OXYGENATION
ERYTHROPOIETINERYTHROPOIETIN
DECREASES
KIDNEY
ERYTHROPOIETIN PRODUCTION
ERYTHROPOEITIN
Glycoprotein MW-34000.
90% formed in endothelial cells of the peritubular capillaries of the renal tubules.
10% formed in liver, hepatic cells & Kupffer cells.
ERYTHROPOEITIN (contd)
Stimuli for production hypoxia, high altitude, anemia, chronic lung or heart diseases, catecholamines, prostaglandins & androgens.
Formed in hours, RBC’s take 2-3 days to appear in peripheral blood.
Intrinsic Factor + Vitamin B12
Vitamin B12 (in a bound state protected by gastric enzymes)
Binds to mucosal cells of ileum
Absorbed into blood by pinocytosis
ABSORPTION OF VITAMIN B 12