55 Granulocytes and Granulocyte Maturation

Michelle To and Valentin Villatoro

Myeloblast/Blast

Notes: Earliest distinguishable and recognizable stage of granulocyte maturation.1

 

Nucleus-to-Cytoplasm Ratio: 4:1 2

 

Nucleoli: 1-51

 

Nucleus:1,3

Round to oval

Central or eccentrically located

Loose, open, evenly stained, reddish-purple, chromatin

 

Cytoplasm:1,2

Dark to light basophilia

May contain granules (up to 20)

Golgi may be seen (pale area next to the nucleus)

 

Normal % in Bone Marrow: 0-2%2

 

Normal % in Peripheral Blood: 0%2


Promyelocyte

Notes: Presence of primary granules marks maturation at the promyelocyte stage.3

 

Nucleus-to-Cytoplasm Ratio: 3:1 2

 

Nucleoli: 1-32

 

Nucleus:1-3

Round to oval

Central or eccentrically located

Reddish-blue chromatin

Fine and slightly coarser chromatin than a myeloblast

 

Cytoplasm:2

Lightly basophilic

Primary (fine, nonspecific) granules present (reddish-purple)

 

Normal % in Bone Marrow: 2-5%2

 

Normal % in Peripheral Blood: 0% 2


Myelocyte

Notes: Presence of secondary granules marks maturation at the myelocyte stage. Primary granules may still be seen but decrease in number as the cell matures. Secondary granules become more predominant as the cell mature and are considered specific to a granulocytic lineage.1

 

The myelocyte is the last stage where the cell is able to undergo mitosis.1

 

Nucleus-to-Cytoplasm Ratio: 2:1 2

 

Nucleoli: Usually not visible2

 

Nucleus:2,3

Round to oval

Eccentrically located

Reddish-purple, slightly clumped chromatin

 

Cytoplasm:2-5

Primary granules may be present in small amounts (Decrease in number as the cell matures).

Secondary (coarse, specific) granules present (Increase in number as the cell matures).

Granulocyte

Cytoplasm Colour

Secondary (Coarse, Specific) Granule Colour

Neutrophil

pink-tan

azurophilic (reddish-purple)

Eosinophil

cream coloured to colourless

eosinophilic (Pale to dark orange)

Basophil

pale blue

basophilic (dark purple-black)

 

Normal % in the Bone Marrow and Peripheral Blood:2,4,5

Granulocyte 

% In Bone Marrow

% In Peripheral Blood 

Neutrophil

5-19%

0%

Eosinophil

0-2%

0%

Basophil

0-1%

N/A


Metamyelocyte

Notes: Cell is no longer capable of mitosis at this stage. Characteristic feature of a metamyelocyte is  the indented nucleus shape (nucleus looks as if it was lightly poked).1

 

Nucleus-to-Cytoplasm Ratio:  1.5:12

 

Nucleoli: Not visible2

 

Nucleus:1-3

Indented (kidney bean shaped); indent is less than one-third of the diameter of the hypothetical round nucleus

Eccentrically located

Dark purple, coarse, clumped chromatin

 

Cytoplasm:2-5

Granulocyte

Cytoplasm Colour

Secondary (Coarse, Specific) Granule Colour

Neutrophil

pink-tan

azurophilic (reddish-purple)

Eosinophil

cream coloured to colourless

eosinophilic (Pale to dark orange)

Basophil

pale blue

basophilic (dark purple-black)

 

Normal % in the Bone Marrow and Peripheral Blood:2-5

Granulocyte 

% In Bone Marrow

% In Peripheral Blood 

Neutrophil

3-22%

0%

Eosinophil

0-2%

0%

Basophil

0-1%

N/A


Band

Notes: Stage shows a nucleus with a larger indentation than a metamyelocyte but it still considered non-segmented.1

 

Nucleus-to-Cytoplasm Ratio:  Cytoplasm predominates 2

 

Nucleoli: Not visible2

 

Nucleus:1,3

Indentation takes up more than one-third of the diameter of the hypothetical round nucleus.

Appears C, U, or S shaped

Centrally or eccentrically located

Dark purple, coarse, clumped chromatin

 

Cytoplasm:2-5

Granulocyte

Cytoplasm Colour

Secondary (Coarse, Specific) Granule Colour

Neutrophil

pink-tan

azurophilic (reddish-purple)

Eosinophil

cream coloured to colourless

eosinophilic (Pale to dark orange)

Basophil

pale blue

basophilic (dark purple-black)

 

Normal % in the Bone Marrow and Peripheral Blood:2,4,5

Granulocyte 

% In Bone Marrow

% In Peripheral Blood 

Neutrophil

7-33%

0-5%

Eosinophil

0-2%

Rare

Basophil

0-1%

N/A


Mature (Segmented) Granulocyte

Nucleus-to-Cytoplasm Ratio: Cytoplasm predominates

 

Nucleoli: Not visible2

 

Nucleus:1-5

Centrally or eccentrically located

Coarse, clumpy, dark purple staining chromatin

Nucleus is separated into lobes which are all connected by chromatin filaments:

Granulocyte

Normal Number of Segmented Lobes

Neutrophil

2-5

Eosinophil

2-3

Basophiil

Usually 2, often obscured by granules

 

Cytoplasm:2,4,5

Granulocyte

Cytoplasm Colour

Secondary (Coarse, Specific) Granule Colour

Neutrophil

pink-tan

azurophilic (reddish-purple)

Eosinophil

cream coloured to colourless

eosinophilic (Pale to dark orange)

Basophil

pale blue

basophilic (dark purple-black), often obscure the nucleus

 

Normal % in the Bone Marrow and Peripheral Blood:2,4,5

Granulocyte 

% In Bone Marrow

% In Peripheral Blood 

Neutrophil

3-11%

50-70%

Eosinophil

0-3%

0-5%

Basophil

<1%

0-1%

 


References:

1. Landis-Piwowar K. Granulocytes and Monocytes. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 97-121.

2. Rodak BF, Carr JH. Neutrophil maturation. In: Clinical hematology atlas. 5th ed. St. Louis, Missouri: Elsevier Inc.; 2017. p. 41-54.

3. Bell A, Harmening DM, Hughes VC. Morphology of human blood and marrow cells. In: Clinical hematology and fundamentals of hemostasis. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 1-41.

4. Rodak BF, Carr JH. Eosinophil maturation. In: Clinical hematology atlas. 5th ed. St. Louis, Missouri: Elsevier Inc.; 2017. p. 65-74.

5. Rodak BF, Carr JH. Basophil maturation. In: Clinical hematology atlas. 5th ed. St. Louis, Missouri: Elsevier Inc.; 2017. p. 75-8.

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A Laboratory Guide to Clinical Hematology by Michelle To and Valentin Villatoro is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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