Maturation of WBC

Rules of Blood Cell Maturation

1. cell size decreases

2. chromatin condenses

3. nucleoli disappear

4. cytoplasm les basophilic

5. N:C raito decreases

Granulopoiesis

HSC

CMP

CFU-GEMM

GMP (CFU-GM)

CFU-G

Myleoblast

Promyleocyte

Myleocyte

metamyleocyte

Band

mature granulocyte

Myleoblast

• size: 14- 20 micrometer

• Nucleus: round to oval, delicate and lacy chromatin, and nucleoli present

• cytoplasm: basophilic (very dark blue), no granules, golgi

• High N:C ratio: 4:1

• may have auer rods (fused granules)

Promyleocyte

• size: 15-21 micrometers

• nucleus: round to oval, delicate and lacy chromatin, nucleoli present usually

• cytoplasm: still basophilic, but lightening; large-blue-black to purple primary granules (Myeloperoxidase, lysozome), golgi

• N:C ratio - 2:1 - 3:1

Myelocyte

• Size: 12-18 micrometers

• Nucleus: becoming smaller, more round (usually) - slightly eccentric - can be flat on one side, chromatin more condensed, nucleoli rarely

• cytoplasm: secondary granules are produced, and primary granules cease or obscured, no peroxidases, prominent golgi, not as basophilic

• N:C ratio - decreased to about 2:1 - 1:1

• last stage to undergo mitosis

Metamyleocyte

• size: 10-18 micrometers

• Nucleus/Chromatin: noticeably clumped chromatin, nucleus is kidney-bean shaped with indentation, Nucleoli absent

• cytoplasm: many secondary granules present

• N:C ratio - 1.5:1 to 1:1

Band

• Size: 10-15 micrometers

• Nucleus/Chromatin: clumped, nucleus is U-shaped, Nucleoli absent

• Cytoplasm: similar to segmented neutrophil

• N:C ratio - approximately 1:1

• Normally 0-5% band neutrophils are found circulating in blood (some bands you may seen in bloodstream)

Mitotic Pool

• myleoblast

• promyelocyte

• myelocyte

Post-Mitotic Pool

• metamyelocyte

• band

• mature cell

Granulopoiesis Series

• maturation process takes about 8-10 days

Distribution of Granulocytes

Bone Marrow Compartment

Pools

• Proliferating/Mitotic —> myeloblast, promyelocyte, myelocyte

• Post-Mitotic/Maturation/Storage —> metamyleocyte, band, mature cell

Distribution of Granulocytes

Peripheral Blood Compartment

Pools

• Marginating —> mature cells waiting on where to go

• Circulating/Functional —> mature cells in the blood ready to go

Monocyte Maturation

• HSC

• CMP

• CFU-GEMM

• GMP (CFU-GM)

• CFU-M

• monoblast

• promonocyte

• monocyte (in blood) or macrophage (in tissue)

Lymphopoiesis

• Lymphoblast

• Prolymphocytes

• lymphocytes

Lymphocyte Activation

• sometimes called a “blast formation”

• 1) Reactive Lymphocyte and Small Lymphocyte 2) Immunoblast 3) Plasmacytoid Lymphocyte 4) Plasma cell

Plasma Cell

• size: 8-20 micrometers

• Nucleus: eccentric placement, chromatin structure is very coarse, no nucleoli, prominent golgi

• cytoplasm: dark blue (deeply basophilic)

• N:C ratio - 2:1 to 1:1

• stimulated B-cell lymphocyte matures to plasma cell to produce antibodies