Note - it is easy to confuse the different leucocytes in blood smears. To identify them, you need to look for the shape of the nucleus, and compare their size, relative to that of a red blood cell. Once you have looked at the examples below - have a go for yourself - click here and see if you can identify the 'mystery' cells. read more
If you mean humans, then our smallest white blood cells, the “small lymphocytes,” start at about 5 micrometers (µm) in diameter. Lymphocytes occur in three size classes, and the “large lymphocytes” can be up to 17 µm. read more
These cells are 12 - 17 µm in diameter - larger than neutrophils, and about 3 times the size of a red blood cell. You can see that eosinophils only have two lobes to their nucleus. These cells have large acidophilic specific granules - these stain bright red, or reddish-purple. read more
The number of leukocytes in the blood is often an indicator of disease, and thus the WBC count is an important subset of the complete blood count. The normal white cell count is usually between 4 × 109/L and 11 × 109/L. In the US this is usually expressed as 4,000 to 11,000 white blood cells per microliter of blood. read more