Nuclei

Nuclear Shape and Density

The nuclei of all leukocytes stain blue due to the basophilic nucleic acids DNA and RNA. Although it takes a little practice to see differences, nuclear shape and color are important criteria used in the identification of leukocytes. Neutrophils are often called "polys" due to their polymorphic nuclei. In short, their nuclei are multi-lobed. Eosinophils and basophils commonly have bilobed or two-lobed nuclei. Monocytes possess large, horse-shoe shaped nuclei with vesicles and lymphocytes typically possess round nuclei. Remember these nuclear shapes/criteria as you examine leukocytes:

Highly variable nuclei with more than two distinct lobes. Narrow nuclear strands connect lobes. These are typically dense, darkly staining nuclei that appear dark blue or almost black.
neutrophils

Basophils and eosinophils possess nuclei with two distinct lobes connected by a narrower band of nuclear material. These bilobed nuclei are commonly hidden behind cytoplasmic granules. These are dense, bluish staining nuclei that are lighter in color than those of neutrophils.
basophils or eosinophils

Monocytes contain nuclei with lighter circular or irregular vesicles. The horseshoe shape of these may not be evident if the angle of view is wrong. These are the least dense of leukocyte nuclei, staining a lighter, "frothy" blue.
monocytes

Lymphocytes and plasma cells possess distinct circular nuclei that can occupy most of the volume of the cell. These are dense, dark-staining nuclei that can appear almost black.
lymphocytes

Now, with these nuclear shapes and densities in mind, see if you can pick up on some of these characteristics in the image to aid in your identification of the cells.

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	Highly variable nuclei with more than two distinct lobes. Narrow nuclear strands connect lobes. These are typically dense, darkly staining nuclei that appear dark blue or almost black. neutrophils
	Basophils and eosinophils possess nuclei with two distinct lobes connected by a narrower band of nuclear material. These bilobed nuclei are commonly hidden behind cytoplasmic granules. These are dense, bluish staining nuclei that are lighter in color than those of neutrophils. basophils or eosinophils
	Monocytes contain nuclei with lighter circular or irregular vesicles. The horseshoe shape of these may not be evident if the angle of view is wrong. These are the least dense of leukocyte nuclei, staining a lighter, "frothy" blue. monocytes
	Lymphocytes and plasma cells possess distinct circular nuclei that can occupy most of the volume of the cell. These are dense, dark-staining nuclei that can appear almost black. lymphocytes