: Erythrocytes: Production and Maturation
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Transcript : Erythrocytes: Production and Maturation
MLAB 1415- Hematology
Keri Brophy-Martinez
The Erythrocyte:
Production and Maturation
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
2
Maturation of Erythrocytes
Erythropoietin (EPO)
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
Reference ranges varies with
Sex
Age
Geographic location
Normal RBC in adults
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
Stem cell - an unspecified
cell that gives rise to a
specific specialized cell, such
as a blood cell
Multipotential and cannot be
identified morphologically
Can self-renew and
differentiate
CFU-GEMM: granulocyte,
Stem Cell
CFU-GEMM
BFU-E
erythrocyte, monocyte,
megakaryocyte
BFU-E: burst forming unit
CFU-E: colony forming unit
CFU-E
EPO
Mature RBC
Terminology Systems
Normoblast
Pronormoblast
Basophilic normoblast
Polychromatophilic
normoblast
Orthochromatophilic
normoblast
Reticulocyte
Erythrocyte
Rubriblast
Rubriblast
Prorubricyte
Rubricyte
Metarubricyte
Reticulocyte
Erythrocyte
Erythropoiesis
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.
8
Maturation Sequence of Erythrocytes
Rubriblast (Pronormoblast)
Size = 14-20 µm
Cytoplasm
Deeply blue (basophilic)
Scant amount, may have a
perinuclear halo
No granules
Nucleus
Large and round
Reddish-purple with fine
chromatin
1-2 nucleoli
may be bluish
N:C ratio ( nuclear: cytoplasmic)
8:1
Maturation Sequence of Erythrocytes
Prorubricyte-(basophilic normoblast)
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
Rubricyte (polychromatic normoblast)
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
Maturation Sequence of Erythrocytes
Metarubricyte - nucleated RBC
(orthochromic normoblast)
Size: 8-10 µm
Cytoplasm
Nucleus
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
Reticulocyte (diffusely
basophilic or
polychromatophilic
erythrocyte
Size: 8-10µm
Cytoplasm
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
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
Mature erythrocyte
Size = 7-8µm
Volume = 80-100 fL
Cytoplasm
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.