The document discusses several lymphatic organs: the spleen, lymph nodes, and tonsils. The spleen is a single organ that filters blood and mounts immune responses. It has a thick capsule, trabeculae that divide it into compartments, white pulp containing follicles with central arterioles, and red pulp with splenic cords and sinusoids. Lymph nodes filter lymph and mount immunity. They have a thin capsule, trabeculae arising from the capsule, cortex and medulla regions. The tonsils include the palatine, lingual, and pharyngeal tonsils which are partially encapsulated lymphatic tissue located in the oral cavity and nasopharynx that protect from bacteria.

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

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

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

5. 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.

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

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

8. 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:

9. 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.

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

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

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

13. 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

14. Filtration
Formation Storage
DestructionBlood
Functions
Immuonological

15. 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.

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

17. 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

18. 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

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

20. 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.

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

22.  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.

23. 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

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

25. 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.

27. 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.

28. Medium sized artery & vein

29. Lymph node

30. The spleen

31. central arteriole

32. Palatine tonsilsPalatine tonsils