Reticuloendothelial system
Objectives
At the end of this lecture, student will be able to
• Explain Reticuloendothelial system
• Name different tissue macrophages
• List functions of RES
Content
• Reticuloendothelial system (RES)
• Classification of RES cells
• Functions of RES
Reticuloendothelial system and tissue macrophages
• Also known as:
– Monocyte-Macrophage system
– Mononuclear Phagocytic System
– Lymphoreticular system.
• Collection of cells united by the common property of phagocytosis.
• It is a generalized phagocytic system located in all tissues.
• Especially in those tissues where large quantities of particles, toxins, and other unwanted substances must be
destroyed
• Ex: spleen, liver, lymph nodes, bone marrow, lungs.
Reticuloendothelial system
• System of cells which have highly phagocytic properties.
• RES consists of:
– Monocytes
– Mobile (wandering) tissue macrophages
– Fixed tissue macrophase or fixed histiocytes
MONOCYTES
• Largest leucocytes.
• Immature cells present in blood, with little ability to fight infectious agent.
• After 72 hours they enter the tissues to become ‘tissue macrophages’.
, • In the tissue they swell to become large in size and cytoplasm is filled with lysosomes.
Functions of monocytes
1. Enter tissue and form tissue macrophages – act as scavengers.
2. Phagocyte several bacteria (up to 100)
3. Engulf large particulate matter, dead tissue cells and senile cells.
4. Along with macrophage involved in phagocytosis & destruction of necrotic material.
5. Co-operate with B & T lymphocyte in both Humoral & Cellular immunity.
WANDERING TISSUE MACROPHAGES
• Monocytes leaving the blood become activated and differentiate into macrophages.
• Those that have recently left the blood are sometimes referred to as wandering macrophages.
• Monocyte changes during maturation:
– A. Increase in cell size
– B. Number and complexity of intracellular organelles increase, i.e., Golgi, mitochondria, lysosomes
– C. Increase in intracellular digestive enzymes
There are two types of wandering reticuloendothelial cells:
1. Free Histiocytes of Blood
i. Neutrophils
ii. Monocytes,
Which become macrophages and migrate to the site of injury or infection.
2. Free Histiocytes of Solid Tissue During emergency, the fixed histiocytes from connective tissue and other organs
become wandering cells and enter the circulation.
Objectives
At the end of this lecture, student will be able to
• Explain Reticuloendothelial system
• Name different tissue macrophages
• List functions of RES
Content
• Reticuloendothelial system (RES)
• Classification of RES cells
• Functions of RES
Reticuloendothelial system and tissue macrophages
• Also known as:
– Monocyte-Macrophage system
– Mononuclear Phagocytic System
– Lymphoreticular system.
• Collection of cells united by the common property of phagocytosis.
• It is a generalized phagocytic system located in all tissues.
• Especially in those tissues where large quantities of particles, toxins, and other unwanted substances must be
destroyed
• Ex: spleen, liver, lymph nodes, bone marrow, lungs.
Reticuloendothelial system
• System of cells which have highly phagocytic properties.
• RES consists of:
– Monocytes
– Mobile (wandering) tissue macrophages
– Fixed tissue macrophase or fixed histiocytes
MONOCYTES
• Largest leucocytes.
• Immature cells present in blood, with little ability to fight infectious agent.
• After 72 hours they enter the tissues to become ‘tissue macrophages’.
, • In the tissue they swell to become large in size and cytoplasm is filled with lysosomes.
Functions of monocytes
1. Enter tissue and form tissue macrophages – act as scavengers.
2. Phagocyte several bacteria (up to 100)
3. Engulf large particulate matter, dead tissue cells and senile cells.
4. Along with macrophage involved in phagocytosis & destruction of necrotic material.
5. Co-operate with B & T lymphocyte in both Humoral & Cellular immunity.
WANDERING TISSUE MACROPHAGES
• Monocytes leaving the blood become activated and differentiate into macrophages.
• Those that have recently left the blood are sometimes referred to as wandering macrophages.
• Monocyte changes during maturation:
– A. Increase in cell size
– B. Number and complexity of intracellular organelles increase, i.e., Golgi, mitochondria, lysosomes
– C. Increase in intracellular digestive enzymes
There are two types of wandering reticuloendothelial cells:
1. Free Histiocytes of Blood
i. Neutrophils
ii. Monocytes,
Which become macrophages and migrate to the site of injury or infection.
2. Free Histiocytes of Solid Tissue During emergency, the fixed histiocytes from connective tissue and other organs
become wandering cells and enter the circulation.
