Eosinophils are granulocytic (WITH granules) white blood cells (WBC). They have a dark red cytoplasm because they pick up the red eosin staining dye in their granules. The nucleus is often a 2 lobed segmented mass. A lot of the time the segments are hard to see, as in this picture, but the 2 ends are more easily visualized as here.

Differences in cytoplam granules of species:

Horses: have large round or oval granules and stain large and intensely
Cats: have small rod shaped granules, are numerous, and stain dark red
Dogs: have round, varying size granules that stain light
Cows, Sheep, Pigs: have round granules which are slightly smaller than horses' and stain pink to red
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