a-short-review-of-histology

Monocytes:

Monocytes are the largest cell to be found in circulating normal blood
They are 15 - 18 microns in diameter and typically show a large horseshoe shaped nucleus
In normal circulating blood they represent about 2-6% of the white blood cells
Like lymphocytes they are sometimes described as agranular leucocytes but in fact contain small cytoplasmic granules
These granules are lysosomes and contain hydrolytic enzymes
When monocytes leave the circulating blood and enter tissue spaces they become known as macrophages
Macrophages are phagocytic
With their lysosomes, they are responsible for the phagocytosis and breakdown of cell debris
In addition, they have important functions in a variety of immune responses
They generally circulate in the blood for 1-3 days before entering tissue spaces where they may be long lived

Monocytes - 2:

This image shows a monocyte
Monocytes are the largest of the circulating white blood cells and typically have a large horse-shoe shaped nucleus and much cytoplasm, as in this example