RBC Maturation

What is the first committed colony-forming unit in the erythrocyte maturation sequence?

Colony Forming Unit: Erythrocytic (CFU:E)

What does CFU:E stand for?

Colony Forming Unit: Erythrocytic

What are the two colony-forming units committed to the red blood cell line?

BFU-E and CFU-E

What does BFU-E stand for?

Burst Forming Unit Erythroid

How long does it take for the BFU-E to mature to the CFU-E?

About 1 week

How long does it take for the CFU-E to become a pronormoblast?

About 1 week

How long does the whole process take from BFU-E to a mature red blood cell?

About 18-21 days

What is the first morphologically recognizable stage in the erythrocyte maturation sequence?

Pronormoblast

What is the size of a pronormoblast?

14-18 µm

What is the N:C ratio of a pronormoblast?

8:1

What is the nuclear shape of a pronormoblast?

Round or oval

What is the nuclear chromatin appearance of a pronormoblast?

Reddish purple with fine chromatin

How many nucleoli does a pronormoblast have?

1-2

What do the nucleoli of a pronormoblast contain?

RNA

What is the cytoplasm appearance of a pronormoblast?

Deeply basophilic, scanty, no granules

Why is the cytoplasm of a pronormoblast deeply basophilic?

Due to the concentration of ribosomes and RNA

Where is a pronormoblast normally found in healthy states?

Only in bone marrow

What is the size of a basophilic normoblast?

10-15 µm

What is the N:C ratio of a basophilic normoblast?

6:1

What is the nuclear shape of a basophilic normoblast?

Round or oval

What is the nuclear chromatin appearance of a basophilic normoblast?

Begins to condense, stains deep purple, not loose and lacy

How many nucleoli does a basophilic normoblast have?

None

What is the cytoplasm appearance of a basophilic normoblast?

Basophilic, slightly more than the blast

What may be seen in the cytoplasm of a basophilic normoblast?

A perinuclear halo

What key process begins at the basophilic normoblast stage?

Hemoglobin production

Where is a basophilic normoblast normally found in healthy states?

Only in bone marrow

What is the size of a polychromatophilic normoblast?

8-14 µm

What is the N:C ratio of a polychromatophilic normoblast?

4:1 to 1:1

What is the nuclear shape of a polychromatophilic normoblast?

Round

What is the nuclear chromatin appearance of a polychromatophilic normoblast?

Coarse and clumped

What is the cytoplasm appearance of a polychromatophilic normoblast?

Blue-gray to pink-gray with wide variation in color

Why is there wide variation in the color of polychromatophilic normoblast cytoplasm?

Due to rapid hemoglobin production

What is the key mitotic feature of the polychromatophilic normoblast?

It is the last stage of mitosis; can no longer divide, only mature

Where is a polychromatophilic normoblast normally found in healthy states?

Only in bone marrow

What is the size of an orthochromatic normoblast?

8-10 µm

What is the nuclear appearance of an orthochromatic normoblast?

Pyknotic (homogeneous), completely condensed, no parachromatin

What is the N:C ratio of an orthochromatic normoblast?

1:2

What is the nuclear shape and position of an orthochromatic normoblast?

Round, small, eccentric (off to the side)

What key event occurs at the end of the orthochromatic normoblast stage?

Nucleus is extruded

What is the cytoplasm appearance of an orthochromatic normoblast?

Just PINK (with only a slight blue tinge)

What does the pink cytoplasm of an orthochromatic normoblast reflect?

Nearly complete hemoglobin synthesis

Where is an orthochromatic normoblast normally found in normal states?

Only in bone marrow

When would an orthochromatic normoblast be seen in peripheral blood?

Anemia or blood loss

What is the size of a polychromatic erythrocyte?

8-10 µm

Does a polychromatic erythrocyte have a nucleus?

No, it was extruded

What is the cytoplasm appearance of a polychromatic erythrocyte?

Slight bluish tinge due to residual ribosomes and RNA

What is a polychromatic erythrocyte observed as on Wright's stained smear?

Polychromasia

What stain is used to see a polychromatic erythrocyte's residual RNA clearly?

Vital stain (reticulocyte stain)

How long is a polychromatic erythrocyte in the bone marrow before moving to peripheral blood?

1-2 days

How long is a polychromatic erythrocyte in peripheral blood before reaching maturity?

About 1 day

What is the size of a mature RBC?

6-8 µm

What is the shape of a mature RBC?

Round, non-nucleated, biconcave disc

What is the area of central pallor in a mature RBC?

1/3 of diameter

What is the average diameter of a mature erythrocyte?

7.2 µm

What is the average thickness of a mature erythrocyte?

2.1 µm

What is the reference range for MCV?

80-100 fL

What is the life span of a mature erythrocyte?

120 days

What is the main function of a mature erythrocyte?

O2 transport to tissues