Transcript : Erythrocytes: Production and Maturation

MLAB 1415- Hematology
Keri Brophy-Martinez
The Erythrocyte:
Production and Maturation
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Part One
Erythropoiesis: Production and maturation of erythrocytes in the
bone marrow
Reticulocyte
Rubricyte
Rubriblast
Polychromatic
normoblast
Pronormoblast
Proerythroblast
Polychromatic
erythroblast
Diffusely basophilic
erythrocyte
Polychromatophilic
erythrocyte
Prorubricyte
Metarubricyte
Mature RBC
Basophilic
normoblast
Orthochromatic
normoblast
Erythrocyte
Basophilic
erythroblast
Orthochromatic
erythroblast
Discocyte
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Maturation of Erythrocytes
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Erythropoietin (EPO)
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The growth factor that stimulates RBC production
Released in response to decreased levels of oxygen in
the body tissues
Produced and released by the kidneys
EPO release is consistent to maintain daily RBC counts
Aged rbc’s are primarily removed by the spleen.
Production and Affects of EPO
Reference Ranges for RBC
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Reference ranges varies with
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Sex
Age
Geographic location
Normal RBC in adults
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Male
4.5-5.5 x 106/µl
Female
4.0 - 5.0 x 106/µl
Infants and children - normals vary by age
Maturation Sequence of Erythrocytes
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Stem cell - an unspecified
cell that gives rise to a
specific specialized cell, such
as a blood cell
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Multipotential and cannot be
identified morphologically
Can self-renew and
differentiate
CFU-GEMM: granulocyte,
Stem Cell
CFU-GEMM
BFU-E
erythrocyte, monocyte,
megakaryocyte
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BFU-E: burst forming unit
CFU-E: colony forming unit
CFU-E
EPO
Mature RBC
Terminology Systems
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Normoblast
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Pronormoblast
Basophilic normoblast
Polychromatophilic
normoblast
Orthochromatophilic
normoblast
Reticulocyte
Erythrocyte
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Rubriblast
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Rubriblast
Prorubricyte
Rubricyte
Metarubricyte
Reticulocyte
Erythrocyte
Erythropoiesis
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As cell develops see structural changes: decrease
in cell volume, condensation of chromatin, decrease
in nuclear to cytoplasmic ratio, loss of nucleoli,
decrease of RNA in cytoplasm, decrease in
mitochondria, and gradual increase in hemoglobin
synthesis.
Nucleus eventually extruded.
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Maturation Sequence of Erythrocytes
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Rubriblast (Pronormoblast)
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Size = 14-20 µm
Cytoplasm
 Deeply blue (basophilic)
 Scant amount, may have a
perinuclear halo
 No granules
Nucleus
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Large and round
Reddish-purple with fine
chromatin
1-2 nucleoli
 may be bluish
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N:C ratio ( nuclear: cytoplasmic)
 8:1
Maturation Sequence of Erythrocytes
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Prorubricyte-(basophilic normoblast)
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Size = 10-16µm
Cytoplasm
 Deeply basophilic indicating RNA
activity needed to produce
hemoglobin
 No granules
Nucleus
 Round, large
 Chromatin more clumped
 0-1 nucleoli
N:C ratio = 6:1
Maturation Sequence of Erythrocytes
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Rubricyte (polychromatic normoblast)
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Size = 10-12µm
 Cytoplasm
 Blue-gray to pink-gray (pink indicates
that hemoglobin production can be
seen)
 Slight increase in amount
 Nucleus
 Round and smaller
 Chromatin more clumped, irregular
 No nucleoli
N:C ratio = 4:1
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Maturation Sequence of Erythrocytes
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Metarubricyte - nucleated RBC
(orthochromic normoblast)
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Size: 8-10 µm
Cytoplasm
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Nucleus
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Pinker indicating larger amounts
of hemoglobin production
Increased amount
Tightly condensed chromatin
(pyknotic)
No nucleoli
Mitosis ends at this stage (no
more DNA synthesis)
Nucleus is extruded at end of this
stage
N:C ratio = 1:1
Maturation Sequence of Erythrocytes
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Reticulocyte (diffusely
basophilic or
polychromatophilic
erythrocyte
 Size: 8-10µm
 Cytoplasm
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Diffusely basophilic due to
residual RNA
Stain with new methylene
blue to see fine reticulum
strands
Hemoglobinization is not
complete
No nucleus present
Present in circulation for
1-2 days
Lab Methods
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New Methylene Blue is a supravital stain it is used to
stain reticulocytes. They cannot be identified as
reticulocytes from Wright’s stain.
Maturation Sequence of Erythrocytes
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Mature erythrocyte
 Size = 7-8µm
 Volume = 80-100 fL
 Cytoplasm
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Pink/red
Biconcave shape
Nucleus - none
Present in circulation for
about 120 days
References
Diggs, L., Strum, D., & Bell, A. (1975).
The Morphology of Human Blood Cells.
North Chicago: Abbott laboratories.
 McKenzie, S. B., & Williams, J. L. (2010).
Clinical Laboratory Hematology . Upper
Saddle River: Pearson Education, Inc.
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