1. Lymphatic organs
Lecture (13) By
Dr.Dalia Kamal Eldein

2. Primary lymphoid organs
Secondary
lymphoid organs
Primary lymphoid organs
Lymph node
Spleen
Tonsils
Bone marrow
Thymus

4. Lymphatic organ
lymph node
Tonsils
Spleen

5. Lymph nodes Lymph nodes are bean-shaped, encapsulated structures
generally 2–10 mm in diameter
distributed throughout the body along the course of the lymphatic vessels, in the chest, neck, pelvis, axilla (armpit), groin region, and in association with the blood vessels of the intestines

6. A. Cortix regions B. Medulla regions
Lymph nodes are divided into two region:
A. Cortix regions
B. Medulla regions

7. Structure of lymph node
The lymph node consists of lymphoid follicles in an outer portion called the "cortex.“, and the inner portion called the "medulla," which is surrounded by the cortex on all sides except for a portion known as the "hilum.“
The hilum presents as a depression on the surface of the lymph node, which makes the spherical lymph node, bean-shaped or ovoid.
The efferent lymph vessel , arteries and veins supplying the lymph node with blood enter and exit through the hilum.

10. A .Cortex
Lies deep to the capsule from which it is separated by a subcapsular sinus
Is incompletely subdivided into compartments by connective tissue septa derived from the capsule

11. The cortex consists of the following components:
Lymph node germinal center
Lymph nodule
Sinusoids
Trabecula and lymph sinus 
Paracortex

12. (a) Lymphoid nodules are composed mainly of :
B cells.
T cells.
Follicular dendritic cells.
Macrophages.
Reticular cells.

13. (b) Sinusoids :
Are Endothelium-lined spaces that extend along the capsule and trabeculae and are known as subcapsular and cortical sinusoids, respectively.

14. (c) The paracortex: located between the cortex and the medulla.
the region where circulating Lymphocytes reach to lymph nodes via post capillary.

15. B . The medulla lies deep to the paracortex and cortex
it is composed of :
Medullary sinusoids
Medullary cords.

16. a. Medullary sinusoids:
are endothelium-lined spaces supported by reticular fibers and reticular cells and frequently contain macrophages.
Medullary sinusoids receive lymph from the cortical
sinuses.
b. Medullary cords:
are composed of lymphocytes and plasma cells.

17. Function of lymph nodes
Lymph nodes have the primary function of producing lymphocytes which help protect the body against microorganisms and harmful foreign particles.
Lymph nodes normally swell when they are actively responding to infection as they fill with the pathogenic cells they filter from the lymph.

18. Tonsils Tonsils: are aggregation of lymphoid tissue.
Lymphoid tissue: is connective tissue characterized by a rich population of lymphocytes
Location :
The site of the tonsils at the opening of both the respiratory and digestive tracts provides a unique and strategic position from which to initiate immunological protection against airborne and ingested pathogens.

19. Tonsils
These lymphoid masses are named according to their location as :
1.Palatine tonsils
2.Pharyngeal tonsil
3.Lingual tonsil

22. 1.Palatine tonsils Location: Located Paired at oropharynx
These are paired ovoid masses of lymphoid tissue
Location:
Located Paired at oropharynx

23. Structure: covered by stratified squamous epithelium
The tonsils have many invaginations which form blind crypts
Tonsillar crypts (lined by a continuous surface of epithelium)
Each crypt surrounded by a zone of varying thickness consisting of mass of lymphoid tissue
Nodule
Capsule :fibrous connective tissue
Septa: separate adjacent crypts

25. 2. Pharyngeal tonsil 2. Pharyngeal tonsil:
This is an accumulation of lymphoid tissue
Location:
In the midline on the roof of the nasopharynx

26. Structure :
Covered by pseudostratified columnar ciliated epithelium
Patches of stratified squamous epithelium may be present
No crypts
Lymphoid tissue
Thin capsule

27. 3. Lingual tonsil: Location : Posterior third of tongue Structure:
One or more wide crypts lined by a stratified squamous epithelium
Lymphatic nodules

28. In the midline on the roof of the nasopharynx
Tonsil
Location
Epithelium
Crypts
Pharyngeal
In the midline on the roof of the nasopharynx
Ciliated pseudostratified columnar epithelium typical of the respiratory tract, with some patches of stratified squamous epithelium observed
Numerous folds of pharyngeal epithelium, not true crypts
Lingual
Posterior third of tongue
Stratified squamous non-keratinising
Multiple monocryptic 'units' with a single shallow crypt each
Palatine
Paired at oropharynx
10-30 deep and sometimes branching crypts (Polycryptic)

29. Spleen Spleen is the largest lymphoid organ in the body
It is the only organ specialized for filtering blood

30. Spleen Structure: connective tissue capsule Trabeculae
sinuses (filled with blood instead of lymph)
Splenic pulp

32. Spleen
Splenic pulp:
The spaces between the trabeculae are occupied by a soft sponge like tissue known as the splenic pulp.
If a freshly cut spleen is examined by naked eye , the splenic pulp have different colors(red or white) in various region.

34. Spleen Splenic pulp is divided into the following two kinds:
1.Red pulp
2.White pulp

35. Spleen 1.Red pulp red pulp consists of: Blood-filled sinusoids
Splenic cords .

36. Spleen 2.White pulp The small masses of white pulp consist of:
lymphoid nodules
Periarteriolar lymphoid sheathes

37. Spleen Function of spleen: 1.Filtration of blood
2.Production of lymphocytes
3.Destruction of old erythrocytes
4.Storage of blood

38. Thank you