3. ERYTHROPOIESIS Flashcards
Mature erythrocytes are
Nonnucleated, biconcave discs with a central pallor that occupies one-third of the cell.
ERYTHROCYTES Life span
120 days
ERYTHROCYTES Main function
transports or carries oxygen from the lungs to the tissues where oxygen is released
ERYTHROCYTES Secondary function
transports carbon dioxide from the tissues to the lungs + buffers the pH of the blood
MATURATION PROCESS rbc
Pluripotent HSC → Common Myeloid Progenitor (CMP) → Burst-Forming Unit Erythroid (BFU-E) → + IL 3, GM-CSF, Kit Ligand → CFU-E → + Erythropoietin → RBC Precursor cells → Mature RBC
earliest committed progenitor; gives rise to large colonies
Burst-Forming Unit-Erythroid
gives rise to smaller colonies of RBC
Colony-Forming Unit-Erythroid
BFU-E → mature RBC time
18- 21 days
BFU-E → CFU-E time
1 week
CFU-E → pronormoblast time
1 week
Pronormoblast → mature RBC time
6 to 7 days
The oxygen carrying component of RBC
Hemoglobin
cell division + maturation
Normoblastic proliferation
Erythrocyte precursor cells
Pronormoblast → Basophilic normoblast → Polychromatic normoblast → Orthochromic normoblast →
Polychromatic erythrocyte
immature RBCs | nucleated precursors in the BM | developing nucleated
cells with normal appearance
Erythroblasts/Normoblasts
mature RBCs
Erythrocytes
Last stage that can undergo mitosis
Polychromatophilic normoblasts
NORMOBLASTIC nomenclature
Pronormoblast
Basophilic normoblast
Polychromatic (polychromatophilic)
normoblast
Orthochromic normoblast
Polychromatic (polychromatophilic)
erythrocyte*
Erythrocyte
RUBRIBLASTIC Nomenclature
Rubriblast
Prorubricyte
Rubricyte
Metarubricyte
Polychromatic (polychromatophilic)
erythrocyte*
Erythrocyte
ERYTHROBLASTIC Nomenclature
Proerythroblast
Basophilic erythroblast
Polychromatic (polychromatophilic)
erythroblast
Orthochromic erythroblast
Polychromatic (polychromatophilic)
erythrocyte*
Erythrocyte
CRITERIA USED IN THE IDENTIFICATION OF ERYTHROID PRECURSORS
❖ Diameter of the cell decreases
❖ Diameter of nucleus decreases more rapidly than the cell | N:C ratio decreases
❖ Nuclear chromatin pattern → coarser, clumped, condensed (raspberry-like appearance)
❖ Nucleoli disappears → cessation of protein synthesis
❖ Cytoplasm changes from blue to gray-blue (Basophilic) to salmon pink (Acidophilic/Eosinophilic)
blueness fades due to
ribosomes + other organelles ↓
Basophilia is caused by
amount of ribosomal RNA
Basic stain
methylene blue
due to its acidic components which attract basic stain
Blueness or basophilia
due to its basic components which attract acid stain
Pinkness or eosinophilia/acidophilia
Acid stain
eosin
Eosinophilia is caused by
accumulation of hemoglobin
Rubriblast (Pronormoblast) SIZE
12-19 µm
Rubriblast
(Pronormoblast) N:C RATIO
8:1
Rubriblast (Pronormoblast) NUCLEUS
Contains 1 or 2 nucleoli
Large, round nucleus
Chromatin is purple red and has a fine pattern
Rubriblast (Pronormoblast) CYTOPLASM
Deep blue (due to ribosomesRNA activity) without granules
Rubriblast (Pronormoblast) FEATURES
❖ Earliest recognizable stage
❖ High RNA activity (needed for
production of CHONs required for Hgb synthesis)
❖ Globin production begins
Prorubricyte (Basophilic Normoblast) CYTOPLASM
Deeper, richer blue
Prorubricyte (Basophilic Normoblast) FEATURES
❖ Most helpful criteria (when comparing with rubriblast): coarser chromatin and absence of nucleoli
❖ Start of hemoglobin synthesis (Hgb pigmentation not yet evident)
Prorubricyte (Basophilic Normoblast) SIZE
12-17 µm
Prorubricyte (Basophilic Normoblast) N:C
RATIO
6:1
Prorubricyte (Basophilic Normoblast) NUCLEUS
Nucleoli may be present in the early
stage but disappears later
Nuclear chromatin is deep purple red and begins to condense