Although most erythroid and myeloid cells decrease in
size as they mature, the cytoplasm becomes relatively
increased in volume, compared to the nucleus. The cytoplasm
becomes less basophilic and increasingly eosinophilic.
Starting at the LEFT, CLICK on the above images to review
RBC maturational morphology.
The pronormoblast (E1) is the earilest recognizable red cell precursor.
They are 15- 20µ in diameter with fine granular chromatin
and 0-2 nucleoli. The cytoplasm is deeply basophilic without granules.
Hemoglobin production becomes evident from the muddy mix
of the blue staining RNA and the red staining hemoglobin
resulting in the greyish cytoplasm of the E4
polychromatophilic normoblast. The chromatin is moderately
condensed.What is the cell to the right of the arrow?
The E5 orthochromatic normoblast is smaller than the E4
stage. In the E5 orthochromatic normoblast hemoglobin is
abundant while ribosomes decrease in number. The nuclear
chromatin is pyknotic and ready to be extruded.
For additional RBC image click on the button below:
Polychromatophilic red cells are larger than mature
erythrocytes and still contain ribosomes and mitochondria,
giving the cell a blue tint. When polychromatic RBCs are
stained with a supravital dye (new methylene blue or cresyl
violet) ribosomes clump to form a blue stained granulars
called reticulum. These are called reticulocytes.
Normal mature erythrocytes are biconcave discs
(approximately 8 um in diameter; 2.5 um thick at the
periphery; 1.0 um thick at the center). This results in an
area of central pallor (about 1/3 the dia.) seen in mature
RBCs stained with Wright's-Giemsa.
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