The lymphatic organs include lymph nodes, tonsils, and the spleen. Lymph nodes are kidney-shaped and filter lymph. They have an outer cortex containing lymph follicles and sinuses, and an inner medulla containing medullary cords and sinuses. The spleen filters blood and produces blood cells. It has trabeculae dividing it into compartments containing white pulp with follicles and red pulp with cords and sinuses. Tonsils contain lymphoid tissue and are located in the palate, base of the tongue, and nasopharynx to protect the respiratory and digestive systems.

2. The lymphatic organs
Dr. Samar AskerDr. Samar Asker

3. LYMPH
NODE

4. Kidney shape
Along the course of
lymphatic vessels to filter
lymph from any organism.
In groups allover the body
e.g. Neck, axilla, thorax,
abdomen& groin.

5. It is divided into
Cortex (outer part).
Medulla (inner part).

6. Formed of
1- Stroma
2- Parenchyma
Lobe
Lobule
Lobule

7. StromaStroma

8. Capsule:Capsule: Dense C. TDense C. T
 cells = fibroblastcells = fibroblast
 Fibers collagenous & elasticFibers collagenous & elastic
 Is thickened at theIs thickened at the hilum due to smooth mshilum due to smooth ms coveredcovered
with adipose CT.with adipose CT.
Reticular fibres:Reticular fibres: cells & fibres in the background stainedcells & fibres in the background stained
brown with {Ag}.brown with {Ag}.

9. Trabeculae:Trabeculae:
C. T septaC. T septa
cells & Fiberscells & Fibers
descend fromdescend from
the cortex into thethe cortex into the
deep surface of thedeep surface of the
capsule.capsule.
They divide theThey divide the
cortex into regularcortex into regular
CompartmentCompartment
In the medullaIn the medulla
they branch tothey branch to
divide it intodivide it into
irregular areas.irregular areas.

10. ParENcHYMParENcHYM
aa

11. In the cortex:
• formed of cortical Lymph follicles either
primary or secondary.
• 1ry lymph follicle:
Rounded , oval or pyramidal

12. Aggregation of
Small lymphocyteslymphocytes mainlymainly BB
and few Tand few T ++ AntigenAntigen
presenting cells & reticularpresenting cells & reticular
cells.cells.
When exposed to specificWhen exposed to specific
antigen, some of theantigen, some of the
lymphocyteslymphocytes will activatedwill activated &&
becomebecome medium-sized & collectmedium-sized & collect
in the centre to form palein the centre to form pale
germinal centregerminal centre

13. Secondary follicle
Follicles with dark
periphery (small
lymphocytes) & pale
germinal centre containing
Activated B lymphocytes
Plasmablasts
Plasma cells
Some T- cells
Macrophages
Reticular cells

14. The thymus dependent Zone:
• the deep part of the cortex
(between cortex &medulla.
• It contains T- lymphocytes
which migrated from the
thymus and post capillary
venules which are lined with
cubical epithelium. Through
which lymphocytes enter &
leave the lymph node.

15. The cortical lymphThe cortical lymph
sinuses:sinuses:
 Occupy the areaOccupy the area
between the corticalbetween the cortical
follicles, capsule &follicles, capsule &
trabeculae. Lined withtrabeculae. Lined with
endothelial cells &endothelial cells &
macrophages . Containmacrophages . Contain
B lymphocytes , plasmaB lymphocytes , plasma
cells & macrophagescells & macrophages

16. In the medulla: formed of
Medullary cords
irregular aggregation of
B lymphocytes
plasma cells
may be continous with
cortical follicle.
Medullary sinuses.
Spaces () medullary cords
lined with epithelial cells
+ macropages
Contain lymph received
from cortical sinuses

17. Circulation of lymph :
• Aff lymph vessels enter through the outer convex
border & poor into the cortical then the medullary
sinuses & drain into efferent lymph vessels which
come out from hilum

18. Cells in lymph node
Stromal cells Parenchymal cells:
Fibroblast
&
Reticular
cells
B lymphocytes
cortex & medulla
Activated B
lymphocytes +
Plasmablasts
in the germinal centre
plasma cells &
macrophages
Endothelial cells
lining the sinuses

19. Function
oF Lymph
node

20. Filtration of
lymph from any
antigen by the
macrophages.
Formation of
lymphocytes in the
germinal centre.
Immunological
function:

21. B- lymphocytes
plasmablasts
plasma cells
Humeral immunity
T helper cell

22. Cell mediated immunity
T- killer cells
direct destruction of
the antigens.

23. The spleen
Single intra abdominal hemo
lymphatic organ.
To filter the blood from any
organism

24. a- Capsule:
Thick C. T. formed of
fibroblast collagen &
elastic fibers containing
smooth muscle fibres.
Is covered by peritoneum.
Stroma:

25. b-Trabeculae:
They arise from the
hilum of spleen may be
from the capsule .
Formed of Thick C. T.
containing smooth
muscle fibres.
Divide the spleen into
irregular
compartments.
The capsule and
trabeculae contain
blood vessels and
nerves.

26. Reticular
CT : formed
of cells &
fibres in the
bacheground
stained only
with
silver{Ag}
stain.

27. Parenchyma
In fresh sections it
shows white spots
on red background
i.e devided into:
White pulp & red
Pulp

28. White pulp=
(Malpighian corpuscle):
Rounded or oval scattered
follicles with an arteriole on
one side called central
arteriole or follecular arteriole.
Formed of reticular CT in which
cells are arranged around the
arteriole into 4 concentric
zones:

29. 1.Thymus dependent zone:
periarterial lymphatic sheath (PALS) contain
T- lymphocytes around the central arteriole
2-Germinal center:
pale area contain activated large B lymphocytes,
plasmablasts, plasma cells & macrophages.

30. Follicular zone= corona: dark contain B
lymphocytes
Marginal zone : at the periphery contain:
T& B lymphocytes plasma cells &
macrophages.

31. Red Pulp:
Formed of :
Splenic cords
Blood sinusoids.

32. Splenic cords=
Billroth cords
The areas between the
white pulp &
bl. Sinusoids contain
blood cells:
(RBCs, WBCs ,lymphocytes ,
monocyts)
plasma cells
Macrophage.

33. Blood sinusoids.
Irregular blood spaces
lined with fenestrated
endothelial cells & non-
continuous basement
membrane For easy passage
of blood cells to the blood.
Macrophages appear in the
wall of the sinusoids to engulf
any foreign bodies

34. Filtration
Formation Storage
DestructionBlood
Functions
Immuonological

35. Functions
1. Filtration of blood from any organism by
macrophages
2. Formation of blood cells : in embryo &
lymphocytes in germinal center
3. Storage of blood cells & platelets.
4. Destruction of RBCs& storage of iron.
5. Immuonological function the reticular
cells trap the antigen & present it to
lymphocytes---- humeral & cell
mediated immunity.

36. Lymph
node
spleen
number multiple Single
Function Filterati
on of
lymph
Immunit
y
Filtration
& stores of
blood
Immunity

37. Lymph node spleen
Capsule Thin, covered with fat
Smooth ms only at
hilum.,
Thick covered with
peritoneum
rich in smooth muscle
Trabeculae Thin arise from the
capsule
Thick arise from the hilum

38. Lymph node spleen
Parenchy
ma
Cortex & medulla
Cortex = lymph follicle &
lymph sinus
The follicles have no
arteriol.
Medulla = Medullary
cords & Medullary
sinuses.
White pulp & red pulp
White pulp = lymph follicle
no sinuses.
The follicle contain arteriole.
Red pulp = splenic cords &
blood sinusoids.
Cells lymphocytes +
macrophages + plasma.
macrophages + plasma cells +
WBCs +RBCs

39. Tonsils
Partially
capsulated
lymphatic
tissue
3 sites:
Palatine tonsils
Lingual tonsil
Pharyngeal Tonsil

40. Palatine tonsilsPalatine tonsils
Two oval masses ofTwo oval masses of
lymphatic tissue under thelymphatic tissue under the
mucous membrane of oro-mucous membrane of oro-
pharynx.pharynx.

41. Lymphatic tissue
of two kinds:
Lymph follicle
with or without
germinal center
Diffuse lymphatic
tissue:
Lymphocytes
plasma cells
macrophage.

42.  Each tonsils is coveredEach tonsils is covered withwith
stratified squamous epitheliumstratified squamous epithelium
which dips into the underlyingwhich dips into the underlying
lymphatic tissue to crypts.lymphatic tissue to crypts.

43. mucous glandsmucous glands
deep to thedeep to the
folliclefollicle theirtheir
ducts open toducts open to
the surface &the surface &
not in the basenot in the base
of the crypt soof the crypt so
inflammation isinflammation is
commoncommon

44. Incomplete
capsule:
separates the
tonsils from the
underlying
structure.
Salivary
corpuscle:
Lymphocyte which
pentrate the epith.
To appear in the

45. Lingual tonsil:
At the base of the tongue
Secondary follicle &
diffuse lymphatic.
 Non keratinised str.
Sqam.epth which form
crypt.
mucous glandsmucous glands openopen
into the base of the crypt.into the base of the crypt.

47. Pharyngeal Tonsil
Single mass of lymphoid
tissue under nasopharynex.
Covered with pseudo
stratified columnar ciliated
epith. with goblet cells
Folded with no crypt
Function :at the beginning
of the respiratory &digestive
systems so protect from
bacteria & produce Ab.