The reticuloendothelial system (RES) is composed of monocytes, macrophages, and certain endothelial cells that work together to defend the body against infection. The RES includes primary lymphoid organs like the bone marrow where cells are produced, and secondary lymphoid organs where the cells function, such as the spleen, lymph nodes, and tonsils. Macrophages located in tissues perform phagocytosis to ingest foreign particles and present antigens, while circulating monocytes mature into tissue macrophages. The RES plays a vital role in immunity and hematopoiesis. Disorders of the RES can include infections, cancers, and blood disorders.

2. TOPIC:
COMPONENTS OF RES
DEVELOPMENT OF RES
FUNCTIONS OF RES

3. RETICULOENDOTHELIAL SYSTEM
Also known as:
• Monocyte-Macrophage System
• Mononuclear Phagocytic System
• Lymphoreticular System

4. RETICULOENDOTHELIAL
SYSTEM ( RES )
• The total combination of monocytes,
mobile macrophages, fixed tissue
macrophages and few specialised
endothelial cells in the bone marrow,
spleen and lymph nodes is called RES.

6. COMPONENT
S OF RES
Basically it is formed
by two different types
of tissues:
• Primary lymphoid
organs
• Secondary
lymphoid organs

7. PRIMARY LYMPHOID
ORGANS
Includes all those organs
where the cells of RES are
formed and get matured.
Includes:
• Bone Marrow
• Thymus
SECONDARY
LYMPHOID ORGANS
Includes the sites where the cells
of RES functions
Includes:
• Lymph nodes
• Tonsils
• Spleen
• Kuppfer cells , Microglia
• MALT ( mucosa associated
lymphoid tissues)

8. RETICULOENDOTHELIAL
SYSTEM
oSystem of cells which have highly phagocytic properties.
oRES consists of:
• Monocytes
• Macrophages
Mobile(wandering) tissue macrophages
Fixed tissue macrophages
• Endothelial cells(bone marrow, spleen, lymph node)

9. MONOCYTE
S
• Largest leukocytes.
• Immature cells present
in blood to fight
infectious agents
• After 72 hours enter
the tissues to become
“tissue macrophages”.
• In tissue they swell to
become large in size
and cytoplasm is filled
with lysosomes.

10. MACROPHAGES
MOBILE TISSUE
MACROPHAGES
• Some macrophages are
mobile and they can
group together to
become one phagocytic
cell in order to ingest
larger foreign particles.
FIXED TISSUE
MACROPHAGES
• Often remains fixed to
their organs they filter
and destroy objects
which are foreign to the
body such as bacteria
and viruses.

11. FIXED TISSUE MACROPHAGES
• Liver Kupffer cells
• Lungs Alveolar macrophages
• Skin Langerhans cells
• Connective tissue Histiocytes
• CNS Microglia
• Bones Osteoclasts
• Spleen/Bone marrow/lymph nodes Reticular or
Dendritic cells

12. KUPFFER’S CELLS OF LIVER

13. ALVEOLAR MACROPHAGES
IN LUNGS

15. FUNCTIONS OF MACROPHAGES
•Engulf inorganic particulate matters(carbon and
dust particles).
•Organic foreign matters such as thorn, fish bone,
catgut are destroyed by enzyme action and lysis.
•Help T & B lymphocyte in the acquired immunity
by presenting antigens.

16. ENDOTHELIAL CELLS

17. FUNCTIONS OF RES
•It plays an important role in formation of RBCs
and WBCs.

18. FUNCTIONS OF RES
• Phagocytic function:
Bacteria, other foreign bodies and tissue debris
engulfed and digested by lysosomes of the
macrophages( direct).
• Destruction of senile red blood cells.
• Storage and metabolism of iron.
• Immune function:
Processing antigens and antibodies production
(indirect).

19. PHAGOCYTOSIS( DIRECT)
• Phagocytosis is a part of natural or innate immune
process
• Macrophages are the powerful Phagocytic cells:
Ingest up to 100 bacteria
Ingest larger particles such as old RBCs
Get rid of waste products

20. • Neutrophils secrete the class
of enzymes called lysozyme
and destroying the bacteria
by the process of
phagocytosis.
• Monocytes engulf large
particulate matters( dead
tissue cell and senile
cells).Also involve in
Phagocytosis.

21. DIRECT ANTI INFLAMMATORY

23. INDIRECT IMMUNE FUNCTION OF
RES
•Ingest foreign body, process it and
present it to lymphocytes.
• Indirect role of RES is when an
antigen( foreign particles) comes in
body our lymphatic system stimulate
white blood cells produce antibodies
to take the action.

24. DISORDERS OF RES
• TUBERCULOSIS (TB) • MALIGNANT DISEASE

25. DISORDERS OF RES
• LEUKAEMIA • LYMPHOMA

26. SPLEEN
• Bean shaped organ
• It is situated in the left
hypochondriac region left
upper part of abdomen,
behind the stomach and
just below the
diaphragm.
• Purplish in colour.
• Weigh about 150g/m
• Largest lymphoid organ.

27. STRUCTURE OF SPLEEN
• White Pulp:
Thick sleeves of lymphoid
tissues that provides the
immune function of the
spleen.
• Red Pulp:
Surround white pulp
composed of vinous
sinuses filled with whole
blood and splenic cords
of reticular connective
tissue rich in
macrophages.

29. FUNCTION OF SPLEEN
• Formation of RBCs
• Removal of unwanted elements from the blood
• Reservoir function
• Role in defence mechanism
• Storage and metabolism of iron

30. SPLENOMEGALY
• The enlargement of spleen is
called splenomegaly.
It happens during the following
conditions:
1. Increased the phagocytosis by
macrophages as in any
infections.
2. Increased destruction of
erythrocytes as in malaria.
3. Abnormal increase in
lymphocytes production as in
leukaemia.

31. DISEASES OF SPLEEN
SICKLE CELL
DISEASE
THROMBO
CYTOPENIA
SPLEEN
CANCER
 This is an
inherited form of
anemia.
 It results in
abnormality in
the oxygen
carrying protein
haemoglobin
found in RBCs.
 If the spleen
becomes
enlarged, it may
have low blood
count platelets.
 Due to low
platelets
spontaneous
bleeding occurs.
 Cancer start in
spleen is primary
cancer.
 If it spreads in the
spleen is known as
secondary cancer.
 Both are rare.