How to get monocytosis


Synonym: mononuclear phagocyte
English: monocyte

1 definition

Monocytes are cellular components of human blood that belong to the leukocyte cell class. When they leave the circulating blood, they develop into tissue-typical macrophages, which are part of the MPS.

2 morphology

Monocytes are around 12-20 ┬Ám in diameter, making them the largest cells in the circulating blood. They have a relatively wide cytoplasmic border, which appears gray-blue in the light microscope according to Pappenheim's staining and can contain fine granulations (lysosomes). The cell nucleus is light and eccentric. It is multifaceted and can be spherical, bean or kidney shaped.

3 histology

4 physiology

As part of monocytopoiesis, monocytes are formed in the bone marrow via a cellular intermediate stage (promonocyte) from special hematopoietic stem cells, the monoblasts. The formation takes place under the influence of growth factors such as GM-CSF (granulocyte-macrophage colony-stimulating factor) and M-CSF (monocyte colony-stimulating factor).

Monocytes circulate in the blood for about 12-48 hours and make up about 2-8% of the total leukocyte population. Like neutrophils, they have the ability to actively migrate into the tissue. There they further differentiate into different cell forms.

5 clinic

A lack of monocytes is called monocytopenia, an increased incidence is called monocytosis.

6 image sources

  • "Monocytes" with the kind permission of Sysmex