This document provides an overview of lymph nodes, including their anatomy, components, and function. Lymph nodes are oval shaped structures distributed along lymphatic vessels that filter lymph and help trap foreign substances. They have an outer cortex containing lymphoid follicles and T cells, and an inner medulla containing sinuses that drain lymph. Lymph nodes play an important role in the immune system by filtering lymph and providing an environment for immune cells like lymphocytes and antigen-presenting cells to interact with antigens.

1. LYMPH NODE
Department of Oral diagnostic medicine and radiology
PRESENTED BY – ZAREESH.S.AKHTAR
1 year MDS

2. CONTENT
◦ Introduction
◦ Components of Lymph nodes
◦ Anatomy of Lymph Node
◦ Physiology of Lymph Node
◦ Function Of Lymph Nodes
◦ Reference

3. Introduction
◦ Lymphoid system is a part of the hematopoietic system
represented by thymus, lymph nodes and spleen.
◦ Lymph nodes form a part of the immune system as well as the
circulatory system.
◦ It collects and drains lymph and are distributed along the course
of the larger lymphatic vessels.

4. ◦ Lymph originates as blood plasma
,in tissue capillary bed ,plasma
leaves the circulatory system to
become interstitial fluid.
10%
100%
90%

5. Components of Lymph nodes
◦ Afferent Lymphatic (entry of lymph )
◦ Capsule - Lymphoid Follicles
◦ Outer Cortex-
1. Macrophages ,
2. Reticular cells ,
3. Follicular dendritic cell
◦ Germinal Centre-
1. B-Lymphocytes cell

6. ◦ Inner Cortex –
1. Macrophages ,
2. Dendritic cell
3. Plasma cell
◦ Medullary sinuses
◦ Hilum
◦ Efferent Lymphatic (lymph goes out )

7. ANATOMY OF LYMPH NODE

8. ◦ Humans have about 450 lymph nodes.
◦ Lymph nodes are small oval ,bean
shaped structures scattered throughout
body along lymph vessels.
◦ Usually of 0.1-2.5 cm length.
◦ May be deep or superficial.
◦ Filter lymph fluid to trap foreign
organisms , cell debris , and tumor cells.

9. ◦ Lymph node has 2 surfaces
◦ 1-Convex surface
◦ Receives Afferent Lymphatics through
which Lymph comes into Lymph node.
◦ These have specialised one way valve.
Afferent
lymph
node
Convex surface

10. • 2-Concave Surface
Also called hilum have 3 important
structure
• -artery
• -vein
• -efferent lymphatics
Concave Surface

11. THE LYMPHOID LOBULE
◦ The lymphoid lobule is the basic anatomical and
functional unit of the lymph node.
◦ Lobules are described in lymph nodes as
physiological compartments.
◦ These compartments contain specific lobular
structures so changes in these compartments
reflect alterations in the lobules.

12. ◦ The (superficial) cortex contains spherical
follicles that are surrounded and separated by
interfollicular (or diffuse) cortex.
◦ The paracortex consists of deep cortical units
(DCUs).
◦ Each lobule has a single DCU that can be
anatomically and functionally divided into a
central DCU and a surrounding peripheral
DCU

13. ◦ Lymph spreads through the subcapsular
sinus over the lobule’s apex, flows down
the sides of the lobule through transverse
sinuses and then flows into the medullary
sinuses.
◦ Lymph from all the lobules drains into a
single efferent lymphatic vessel that exits
the node at the hilus .

14. Lymph nodes –Capsule ,Cortex and Medulla
• The cortex, paracortex and
medulla are each composed of
specific areas of the lymph
node’s lobules and sinuses.
• The lobules lie together within
the sinus system .

15. • The body of lymphoid
islands is united by its
lymphocytes which move
back and forth between the
lobules for antigens.

16. Capsule of the lymph node
◦ Lymph nodes are surrounded by a fibrous
connective tissue capsule that enters the
organ as trabeculae that defines a cortex
and medulla.
◦ The capsule and trabeculae are the source
of reticulin fibers that are found through
the node and form the main supporting
network of the organ

17. ◦ Beneath the capsule is a
subcapsular sinus into
which lymph flow from
the afferent lymphatic
vessels

18. Reticulin Framework
◦ The reticular fibers are delicate ,black –staining
strand supporting the parenchyma and contributing
to the perivascular connective tissue
◦ The reticular meshwork is a, porous, sponge-like
tissue composed of stellate, spindle shaped or
elongated fibroblastic reticular cells (FRCs) and their
reticular fibers
◦ Reticular Fibers i.e. Type III Collagen

19. ◦ Macrophages known as sinus histiocytes cling to the reticular meshwork .
◦ They occur in clusters, especially in transverse sinuses near the capsule,
and are relatively infrequent in the subcapsular sinus.
◦ Sinus histiocytes increase in response to the need for particle clearance and
may completely fill the sinuses (sinus histiocytosis)
◦ Some sinus histiocytes originate in the tissues and migrate to the sinuses
after antigenic stimulation .

20. ◦ Lymphatic sinuses
◦ Subcapsular sinuses
◦ Trabecular sinuses / cortical sinuses

21. CORTEX
◦ Cortex is divided into
◦ 1-Outer cortex
◦ Filled with lymphoid follicles.
◦ Outer edge of follicle contains
more T-cells.
◦ Inner Germinal center is the site
of B-cells proliferation.

22. Cellular Zones Of Lymph Nodes
◦ A Primary follicle is
uniformly populated
by small ,quiescent
lymphocytes
◦ A Secondary follicle
has a germinal center.

23. Zones of Germinal Centre
• In the ‘dark zone’ the B cells [centroblast]undergo rapid proliferation.
• ‘Light zone’ B cells occur as centrocytes.
• The mantle zone is produced as surrounding cells are marginalized by the rapidly
growing center.

24. ◦ 2-Inner cortex or paracortex
◦ Contain T-cells randomly
arranged ,
◦ Macrophages and dendritic
cells

25. Medulla
◦ Medulla is the inner collecting area of sinuses
◦ The medulla consist of anastomosing cords of lymphatic tissue .
◦ The medullary cords interspersed with the medullary sinuses that
drain the lymph from the node into the efferent lymphatics vessels
that are located at the hilus

26. Hilum
◦ The hilum has numerous arteries and
veins .
◦ The lymph leaves the lymph node via
the efferent lymphatics vessels with
valves at the hilum

27. PHYSIOLOGY OF
LYMPH NODE

30. Function Of Lymph Nodes
◦ Lymph nodes play an important role in the defense mechanism of the body.
◦ They filter out micro-organism (such as bacteria ) and foreign substance
such as toxins , etc.
◦ Filter lymph ,thereby promoting lymphocyte contact with antigen
◦ Provides necessary microenvironment for antigen – dependent
differentiation.
◦ New lymphocytes are manufactured in the lymph nodes.

31. ◦ Inderbir singh’s textbook of human histology
◦ Grey’s Anatomy
◦ Medical Physiology by K Sembulingam
◦ Textbook of Physiology by A K Jain
◦ Lymph Nodes go with the flow –JEM journal of experimental Medicine
◦ Normal Structure ,Function , and Histology of Lymph Nodes.-Toxicologic
Pathology ;Cynthia L. Willard – Mack
◦ Lymph Nodes: The Unrecognized Barrier against Pathogens
Ania Bogoslowski and Paul Kubes
ACS Infectious Diseases 2018 4 (8), 1158-1161
DOI: 10.1021/acsinfecdis.8b00111
Reference