The reticuloendothelial system (RES) consists of macrophages found in the liver, brain, lungs, bone marrow, lymph nodes, and intestine that help defend the body. RES cells are classified into two types: fixed tissue macrophages located in connective tissue, blood vessels, and organs like the spleen and liver, and wandering monocytes and neutrophils in the blood and lymph system. The RES performs important functions like phagocytosis of pathogens, secretion of cytokines and growth factors, and removal of old red blood cells and carbon particles from the body.

1. Dr. Maria Idrees
PT (TUF)
Ms nmpt (RIU)

2. Composition of RES
 Kupffer cells of liver
 Microglia of brain
 Alveoler macrophages
 Bone marrow lymph nodes
 Macrophages in the intestine

3. Reticulo endothelial cells are found in the following
structures:
 Endothelial lining of vascular and lymph channels
 Connective tissue and some organs like spleen, liver,
lungs, lymph nodes, bone marrow etc.

4. Classification
Classified into 2 types
 Fixed reticuloendothelial cells or tissue macrophages
 Wandering reticuloendothelial cells

5. Fixed reticuloendothelial cells
Also called fixed histiocytes because these cells are usually
located in the tissues.
Tissue macrophages are present in following area
 Connective tissue
 Endothelium of blood sinusoids
 Reticulum
 CNS
 Lungs
 Subcutaneous tissue

6. Wandering reticuloendothelial cells
Also called free histiocytes
 2 types
1. Free histiocytes of blood
Neutrophils
Monocytes
1. Free histiocytes of solid tissue

7. Functions of RES
 Phygocytic function
 Secretion of bactericidal function
 Secretion of IL-1-6-12
 Secretion of TNF
 Secretion of CSF
 Secretion of PDGF
 Removal of carbon particles and silicon
 Destruction of senile RBCs
 Destruction of Hb

8. Gross & microscopic structure