Define the Fixed Type of Macrophages

The fixed types are located permanently in certain organs, which include:

• Lungs - alveolar macrophages.
• Liver - kupffer cells.
• Renal glomeruli - mesangial cells.
• Brain - microglial cells
• Connective tissues - histocytes

They are also found in the spleen, lymph nodes and in the endothelium. They catch hold of the microbes and dead cells that are carried along in the blood and lymph and are trapped in the spleen, lymph nodes etc. The wandering and fixed macrophages together form reticular endothelial system.