Lecture 5 - Leukocyte Development & Morphology Flashcards
What are the Granulocytic and Mononuclear Leukocytes?
Granulocytic - neutrophils - eosinophils - basophils Mononuclear - lymphocytes - monocytes
Neutrophils
Segmented nucleus Condensed chromatin Pale cytoplasmic granules - small - many - uniform
Variation in Morphology of ‘Normal’ Neutrophils
Orientation of cells Orientation of lobes Number of lobes Amount of 'twisting' of lobes Degree of segmentation Prominence of granules
Eosinophils
Segmented nucleus Condensed chromatin Cytoplasmic granules - eosinophilic (orange/red) - high density - larger than neutrophil Cytoplasm pale basophilic (blue)
Basophils
Segmented nucleus Condensed chromatin Cytoplasmic granules - dark basophilic - high density - often obscure nucleus
Monocytes
Largest of leukocytes Variable nucleus shape - horse-shoe - irregular Reticular chromatin pattern Moderate N:C ratio Cytoplasm - grey-blue colour - often notable vacuoles - primary granules may be evident (sparse, small, basophilic)
Lymphocytes
Smallest of leukocytes
Round to ovoid shaped nucleus
Dense, condensed chromatin
Small amount of basophilic cytoplasm at periphery
Types of Leukopoiesis
All of these occurs in bone marrow (of adults)
Myelopoiesis - production of leukocytes
Granulocytopoiesis - production of granulocytes
Monocytopoiesis - production of monocytes
Lymphopoiesis - production of lymphocytes
Myelopoiesis
Identifiable morphological stages of development - Romanowsky stain and light microscopy Many preceding stages - stem cells - CFU-GM - CFU-G Continuum of development
Granulocytopoiesis
Shape of nucleus becomes more complex with maturity
N:C decreases with maturity
Granules
- primary granules form initially (promyelocyte)
- decrease as cell matures
- secondary granules form later (myelocyte)
- increase in number/density as the cell matures
Frequency of Leukocytes in Peripheral Blood
From most to least
- neutrophils
- lymphocytes
- monocytes
- eosinophils
- basophils
Morphological Atypia in Granulocytes
Dohle bodies
- appear as grey-blue inclusions in the cytoplasm of activated neutrophils
- represent segments of endoplasmic reticulum/aggregates of ribosomes
- usually found on the periphery of granulocyte
Toxic granulation
- prominent basophilic-azurophilic cytoplasmic granules
- often accompanies Dohle bodies
Band Neutrophils
Hypo-segmented nucleus -> nuclear immaturity
Increased concentration of bands termed ‘left-shift’
Also applied when less mature stages present
Reactive Lymphocytes
Characterised by:
- larger size
- larger nucleus
- irregular cell outline
- decreased chromatin density
- decreased N:C ratio
- increased amount of cytoplasm
How to tell the difference between a neutrophil with toxic granulation and a basophil?
Neutrophil with toxic granulation - many small regular granules
Basophil - many granules with varied size and shape
