1. Microscopic Structure of Lymph node, Spleen, Thymus and Tonsil
Dr. Sama ul Haque

2. Objectives Understand the location of lymphatic organs.
Discuss the microscopic features of Lymph Node.
Discuss the microscopic features of Spleen.
Discuss the microscopic features of Thymus.
Discuss the microscopic features of Tonsil.

3. Location of Lymphatic Organs

4. Lymph Node

5. Lymph Node Covered by a capsule which extends to form Trabeculae.
Divided into outer cortex and inner medulla.
OUTER CORTEX contains:
Lymphatic nodules with germinal center
INNER MEDULA contains:
Medullary Cords and Medullary Sinus

6. Lymph node SC --- Subcapsular Sinus C Cortex M Medulla H Hilum LN --- Lymphatic Nodules T Trabeculae MS --- Medullary Sinus MC --- Medullary Cords
Capsule SC C M MS H MC T
Lymphatic nodules لاحـظوا الـ LN

7. Lymph node CT --- Connective tissue C Cortex M Medulla P Paracortex LN --- Lymph Node T Trabeculae MS --- Medullary Sinus MC --- Medullary Cords
Lymphatic nodules لاحـظوا الـ

8. C -- Capsule, S -- Subcapsular Sinus, N -- Lymph Node
Lymphatic nodules لاحـظوا الـ
C -- Capsule, S -- Subcapsular Sinus, N -- Lymph Node

9. Lymph node
Lymphatic nodules لاحـظوا الـ

10. Lymph node
Lymphatic nodules لاحـظوا الـ

11. Flow of Lymph

12. Spleen

13. Spleen Covered by a capsule which extends to form Trabeculae.
Trabeculae contains trabecular arteries & Veins.
Lymphatic nodules with germinal centers constitutes the white Pulp.
Central artery passes through lymphatic nodules.
Red or Splenic pulp contains pulp arteries, Venous sinuses and Splenic cords (Cords of Billroth).

14. Spleen

15. Spleen

16. Splenic Cords and Splenic Sinusoids

17. Open and Closed Circulation in Spleen

18. Thymus

19. Thymus Covered by a capsule which extends to form Trabeculae.
Trabeculae extends inwards to forms numerous incomplete lobules (lobulated appearance).
Each lobule consists of dark staining outer cortex and a light staining inner medulla.

20. Thymus
Cortex contains densely packed lymphocytes (No lymphatic nodules).
Medulla contains fewer lymphocytes but more epithelial reticular cells.
Medulla also contains Thymic (Hassall’s) Corpuscles.
Thymic (Hassall’s) Corpuscles are oval structures consisting of round whorls of flattened epithelial cells.

21. Thymus

22. Thymus

23. Palatine Tonsil

24. Palatine Tonsil
Surface of the Tonsil is covered by Stratified Squamous nonkeratinized epithelium.
Tonsil is invaginated by deep grooves called Tonsillar Crypts.
Below epithelium lymphatic nodules are present in the connective tissue.
Dense connective tissue underlies the palatine tonsil and forms capsule.

25. Palatine Tonsil

26. Thank You