LYMPHOID TISSUE PART 1
LYMPH NODES AND GUT-ASSOCIATED
Dr. Larry Johnson
Texas A&M University
Objectives
Lymph node
Describe the structural organization of lymphoid tissue in general
and of the thymus, lymph nodes, lymph nodules (follicles) and
spleen. Detail how antigens are removed from the lymph and the
blood via the sinuses and reticular cells of the lymph nodes and
the spleen. Trace the movements of cells and fluid through the
lymph node and the spleen.
Part 1 Lymph nodes and gut-associated
lymphoid tissue
Part 2 Spleen and thymus
Spleen
FUNCTIONS OF THE IMMUNE SYSTEM
• PROTECTION AGAINST FOREIGN
INVADERS INTO BODY
• PRODUCE / PROTECT GERM FREE
ENVIRONMENT OF THE BODY
EXAMPLES OF IMMUNE RESPONSE
• REACTION AGAINST MICROORGANISMS: BACTERIA,
VIRUSES, PARASITES
Appendix
EXAMPLES OF IMMUNE RESPONSE
• REACTION AGAINST MICROORGANISMS: BACTERIA,
VIRUSES, PARASITES
• REACTION AGAINST TUMOR CELLS
Appendix
EXAMPLES OF IMMUNE RESPONSE
• REACTION AGAINST MICROORGANISMS: BACTERIA,
VIRUSES, PARASITES
Appendix
• REACTION AGAINST TUMOR CELLS
• ALLERGIC REACTIONS: HAY FEVER, POISON IVY
http://www.greenlifestyle.be
EXAMPLES OF IMMUNE RESPONSE
• REACTION AGAINST MICROORGANISMS: BACTERIA,
VIRUSES, PARASITES
Appendix
• REACTION AGAINST TUMOR CELLS
• ALLERGIC REACTIONS: HAY FEVER, POISON IVY
• AUTOIMMUNE REACTION: ARTHRITIS, TYPE I
DIABETES
http://www.greenlifestyle.be
EXAMPLES OF IMMUNE RESPONSE
• REACTION AGAINST MICROORGANISMS: BACTERIA,
VIRUSES, PARASITES
Appendix
• REACTION AGAINST TUMOR CELLS
• ALLERGIC REACTIONS: HAY FEVER, POISON IVY
• AUTOIMMUNE REACTION: ARTHRITIS, TYPE I
DIABETES
• GRAFT REJECTION
http://www.greenlifestyle.be
TYPES OF IMMUNE RESPONSE
•ANTIBODY - MEDIATED
GLYCOPROTEINS RECOGNIZE AND
BIND TO ANTIGENS
TYPES OF IMMUNE RESPONSE
•ANTIBODY - MEDIATED
GLYCOPROTEINS RECOGNIZE AND
BIND TO ANTIGENS
•CELL - MEDIATED
SPECIFICALLY ACTIVE CELLS
RECOGNIZE CELL - BOND
ANTIGENS
TYPES OF IMMUNE RESPONSE
•ANTIBODY - MEDIATED
GLYCOPROTEINS RECOGNIZE AND
BIND TO ANTIGENS
•CELL - MEDIATED
SPECIFICALLY ACTIVE CELLS
RECOGNIZE CELL - BOND
ANTIGENS
T-cells: primary defense against intracellular pathogens,
cell-mediated response
B-cells: primary defense against extracellular pathogens,
transform into plasma cells that produce antibodies for
antibody-mediated response
ROLES AND SPECIFIC ACTIONS OF
ANTIOBODIES IN IMMUNITY
COMPLEMENT - MEDIATED LYSIS
OPSONIZATION - PROMOTE PHAGOCYTOSIS
TOXIN NEUTRALIZATION
PREVENTION OF MICROBIAL BINDING TO
MUCOSAL SURFACE
VIRUS NEUTRALIZATION - INTERFERES WITH
CELL PENETRATION
DEGRANULATION OF MAST CELLS
http://www.youtube.com/watch?v=Ys_V6FcYD5I&feature=related
http://www.youtube.com/watch?v=HNP1EAYLhOs
LIFE CYCLE OF LYMPHOCYTES
FETAL ORGANS
BONE MARROW
PRIMARY LYMPHOID ORGANS
(ANTIGEN INDEPENDENT
DEVELOPMENT)
- THYMUS - T LYMPHOCYTES
- BONE MARROW - B LYMPHOCYTES
LIFE CYCLE OF LYMPHOCYTES
FETAL ORGANS
BONE MARROW
PRIMARY LYMPHOID ORGANS
(ANTIGEN INDEPENDENT
DEVELOPMENT)
- THYMUS - T LYMPHOCYTES
- BONE MARROW - B LYMPHOCYTES
SECONDARY LYMPHOID ORGANS
(ANTIGEN DEPENDENT
DEVELOPMENT)
• LYMPH NODES
• LYMPHOID NODULES
• SPLEEN
Lymphoid organs
Organ
Characteristics
Structure
Lymph nodes
•
•
•
•
Filters lymphatic fluid
Present where small lymphatics converge
Contain many reticular cells
APCs present antigen to T and B
lymphocytes
• Post-capillary high endothelial venules
• Dense irregular capsule (Type I collagen)
• CT trabeculi extend from capsule inwards to partially
divide interior
• Subcapsular sinus
• Primary nodules – immunologically inactive, no
germinal center
• Secondary nodules – active with germinal center
Spleen
• Filters blood and supports lymphocyte
differentiation
• Dense irregular CT capsule
• White pulp
• Immune component
• PALS – periarteriolar lymphatic sheaths
• Red pulp
• Dense reticular fiber network
• Filters blood
Thymus
• Lymphoepithelial organ
• Atrophies at puberty, fully developed at birth
• Proliferation and differentiation of T
lymphocytes
• Blood-thymus barrier
•
•
•
•
Irregular CT capsule
Incomplete subdivisions into lobules
Dense outer cortex & loose medulla
Unique characteristic: Hassall’s (thymic) corpuscles
LYMPH NODE
44
Hilum = single site for blood entry
and exit
Lymph node Efferent
lymphatic
duct
44
44
Lymph node
Afferent
lymphatic
duct
116
Efferent lymphatic
duct
Both afferent and efferent
lymphatic vessels characterize
lymph nodes.
116
Slide 44: Lymph Node
Medullary
sinus
Medulla
Medullary
cords
Cortex
lymph node
follicles
Germinal
center
Trabeculae
Capsule
Subcapsular
sinus
LYMPH NODES - FILTRATION OF LYMPH
BASIC STRUCTURE - RETICULAR FRAMEWORK
LYMPH NODES - FILTRATION OF LYMPH
BASIC STRUCTURE - RETICULAR FRAMEWORK
LYMPH NODES - FILTRATION OF LYMPH
BASIC STRUCTURE - RETICULAR FRAMEWORK
Slide 45: Lymph node (reticulum silver stain)
Lymph node with reticular stroma
Reticular cells
Type III collagen
The reticular fiber stroma functions as the structural framework
of lymph organs.
Slide 44: Lymph Node
Small lymphocytes in cuff
Lymph node follicle (nodules) with germinal center and cuff
Lymph nodes have germinal centers to produce T
and B lymphocytes against the specific antigen each
had encountered in this lymph node.
Medium lymphocytes in
germinal center
LYMPH NODES - FILTRATION OF LYMPH
CORTEX
• FOLLICLES - B LYMPHOCYTES
• PERIFOLLICULAR - T LYMPHOCYTES
Lymph node follicle
1. Germinal center
2. Lymphocyte
3. Reticulum cell
Lymph node follicle
1. Germinal center
2. Lymphocyte
3. Reticulum cell
LYMPH NODES AND LYMPHOID TISSUE
Cord
Blood sinus
Lymph sinus
Lymphocytes
in cortex
LYMPH NODES AND LYMPHOID TISSUE
Cord
Blood
vessel
Macrophages containing debre
in cords
Lymph
sinus
Lymph
sinus
19754
19754 Lymph sinus in lymph node
Cord
Cord
Cord
LYMPH NODES AND LYMPHOID TISSUE
LYMPH FLOW
Parafollicular region
Parafollicular region
Parafollicular region
High endothelial cells of a venule
Parafollicular region
LYMPH NODES AND LYMPHOID TISSUE
LYMPHOCYTE CIRCULATION
• HIGH ENDOTHELIAL VENULES
RECEPTORS FOR T&B CELLS ONLY
• ONE-WAY TRAFFIC
LYMPH NODES AND LYMPHOID TISSUE
LYMPHOCYTE CIRCULATION
HIGH ENDOTHELIAL VENULES
RECEPTORS FOR T&B CELLS ONLY
ONE-WAY TRAFFIC
Slide 44: Lymph Node
High endothelial venule
Copyright McGraw-Hill Companies
Macrophage
Reticular cell
Plasma cell
High endothelial venule
Copyright McGraw-Hill Companies
High endothelial venule
High endothelial
cells of a venule
High endothelial
cells of a venule
High endothelial
cells of a venule
High endothelial venules have receptors for T and B
lymphocytes and allow:
• Enable naïve lymphocytes to move into of lymph nodes
from the blood to find it’s unique antigen
• Entry point for 90% of lymphocytes into lymph nodes
others enter through afferent lymph vessels
All lymphocytes inside the node leave via the efferent lymph vessel.
Blood flow
• Artery > arteriole > capillary around lymphatic nodule > postcapillary high endothelial venule (T & B lymphocyte receptors)
> venule > vein
Lymph flow
• Afferent lymphatic vessels (many) > subcapsular sinus >
trabecular (cortical) sinus > medullary sinus > efferent
lymphatic vessel
INDUCTION OF RESPONSE
•PERIPHERAL ORGAN NEEDED TO GET ANTIGEN AND
RESPONSIVE CELL TO INTERACT
• LYMPHOCYTE RECIRCULATING
• APPROPRIATE CONTEXT
RECYCLING OF
LYMPHOCYTES
THROUGH
LYMPH NODES
High endothelial
cells of a venule
LYMPH NODES –
FILTRATION
OF LYMPH TO ALLOW
POTENIALLY ACTIVE
LYMPHOCYTES TO
SEE/RESPOND TO ITS
ANTIGEN IF PRESENT
IN THE LYMPH.
An infected (stimulated)
lymph node would be
swollen with leukocytes.
Summary of Lymph Nodes
BASIC STRUCTURE
• LYMPHATIC VESSELS
• VASCULATURE
• RETICULAR FRAMEWORK
CORTEX
• FOLLICLES - B LYMPHOCYTES
• PERIFOLLICULAR - T LYMPHOCYTES
MEDULLA
• CORDS
• SINUSES
Gut-associated lymphoid tissue
Slide 62: Terminal ileum
Peyer’s patches
Germinal center
Peyer’s Patch
M (microfold) cells Simple columnar epithelium
M cells in the gut
The function of the M [microfold]) cells is to
transport (present) organisms and particles
from the gut lumen to immune cells across the
epithelial barrier.
PEYER PATCHES
204
PEYER PATCHES
in the human appendix
145
Fundic stomach
Esophagus and trachea, monkey
Tonsil
Slide 46: Palatine tonsil
Lymph nodules of tonsil
Tonsillar crypts
Nonkeratinized stratified squamous
epithelium of tonsillar crypt
Slide 52: Tongue (lingual tonsil)
Scattered nodules
Tonsil
419
419
Tonsil
If a patient had a tumor on the posterior third of
their tongue, the lingual lymph tonsils (situated
along surface of the posterior third of the tongue)
would need to be check for metastasis.
END of Part 1
Next: Lymphoid tissue
Part 2 Spleen and thymus
LYMPHOID TISSUE
PART 2 SPLEEN AND THYMUS
Dr. Larry Johnson
Texas A&M University
Objectives
Lymph node
Describe the structural organization of lymphoid tissue in general
and of the thymus, lymph nodes, lymph nodules (follicles) and
spleen. Detail how antigens are removed from the lymph and the
blood via the sinuses and reticular cells of the lymph nodes and
the spleen. Trace the movements of cells and fluid through the
lymph node and the spleen.
Part 1 Lymph nodes and gut-associated lymphoid
tissue
Part 2 Spleen and thymus
Spleen
Functions of the spleen are the filtration of blood; destruction of aged erythrocyte; pitting of
reticulocytes, production site of lymphocytes and antibodies from differentiated plasma cells,
and activated lymphocytes.
Open circulation involves the dumping of blood into splenic cords from penicillar arterioles.
From here the formed elements of blood must reenter circulation by passing through narrow
slits through endothelial stave cells. This steps filters the blood. The filtered blood passes into
the venous sinusoids and returns to circulation, but macrophages destroy the old and dead
cells.
Function of the thymus is to produce T lymphocytes in an antigen free environment blood thymus barrier in cortex of thymus.
SPLEEN
OVERALL STRUCTURE
VASCULAR ARRANGEMENT
WHITE PULP
• CENTRAL ARTERY
• PERIARTERIOLAR LYMPHATIC SHEATH
• FOLLICLES - B LYMPHOCYTES
RED PULP
• VENOUS SINUSES
• PULP CORDS (BILLROTH’S STRANDS)
• MARGINAL ZONE
http://www.youtube.com/watch?v=0CqWulccLMo
SPLEEN
OVERALL STRUCTURE
VASCULAR ARRANGEMENT
Spleen
Spleen (reticulum stain)- capsule and reticulum
fibers
Spleen
122
WHITE PULP
SPLEEN
• CENTRAL ARTERY
• PERIARTERIOLAR LYMPHATIC SHEATH
• FOLLICLES - B LYMPHOCYTES
RED PULP
• VENOUS SINUSES
• PULP CORDS (BILLROTH’S STRANDS)
• MARGINAL ZONE
Spleen:
1. Central artery
2. Periarteriolar lymphatic sheath
3. Red pulp
Spleen
122
Marginal zone
Spleen
central artery
122
Spleen
central artery
PENICILLARY ARTERIES
Marginal zone
122
Splenic red pulp:
1. Venous sinus
2. Littoral cell
3. Billroth’s strand
218
Spleen reticulum:
1. Reticulum fiber
2. Billroth’s strand
3. Sinuses
SPLEEN
RETICULAR FIBER FRAMEWORK
• RETICULUM CELL - MESODERM
BLOOD FLOW
SPLEEN
• PENICILLARY ARTERIES
macrophages
BLOOD FLOW
cells = picketSPLEENLittoral
fence type endothelial
• PENICILLARY ARTERIES
BILLROT
(splenic)’S
STRANDS
cells of vascular sinus
Litteral cells of spleenic venial
Spleen #19752 (UT117?)
117
Litteral cells of spleenic venial
Spleen # 19752 (UT117?)
117
SPLEEN
BLOOD FLOW
• FILTRATION
• REMOVAL OF OLD RED
BLOOD CELLS
Littoral cells = picketfence type endothelial
cells of vascular sinus
SPLEEN
BLOOD FLOW
• FILTRATION
• REMOVAL OF OLD RED
BLOOD CELLS
Blood flow in spleen
Copyright McGraw-Hill Companies
Slide 47: Spleen
Capsule
Trabeculae
Red pulp
White pulp
Slide 47: Spleen
White pulp
Central artery surrounded by peri-arterial
lymphatic sheath
Red pulp
Splenic cords
(Billroth’s strands)
Venous sinuses
Blood flow in spleen
Copyright McGraw-Hill Companies
SPLEEN
BLOOD FLOW
• FILTRATION
• REMOVAL OF OLD RED BLOOD CELLS
SPLEEN
BLOOD FLOW
• FILTRATION
• REMOVAL OF OLD RED BLOOD CELLS
THYMUS
GROWTH PATTERN - REGRESS AFTER
CHILDHOOD
RETICULUM FRAMEWORK – EPITHELIUM
(from endoderm)
CORTEX - ABSENCE OF EXOGENOUS
ANTIGENS
• EPITHELIAL MICROENVIRONMENT
• LYMPHOPOIESIS
• BLOOD-THYMUS BARRIER
MEDULLA
Thymus maturation
Copyright McGraw-Hill Companies
THYMUS
GROWTH PATTERN - REGRESS AFTER CHILDHOOD
THYMUS
RETICULUM FRAMEWORK - EPITHELIUM
EPITHELIUM
THYMUS
CORTEX - ABSENCE OF EXOGENOUS ANTIGENS
• EPITHELIAL MICROENVIRONMENT
• LYMPHOPOIESIS
• BLOOD-THYMUS BARRIER (cortical barrier only)
MEDULLA
THYMUS
CORTEX AND MEDULLA
Slide 48: Thymus (1 yr old child)
Medulla
Cortex
Capsule
Septae
Medulla with lymphocytes
and reticular cells
Cortex with tightly
packed lymphocytes
Hassall’s corpuscle
THYMUS
CORTEX
EPITHELIUM
THYMUS
CORTEX
Mitosis
Mitosis
THYMUS
CORTEX
T cell death
THYMUS
CORTEX AND MEDULLA
CORTEX
MEDULLA
THYMUS
MEDULLA
Hassall’s corpuscles
Clinical Correlation
Infections often cause enlargement of lymph nodes that receive lymph from
the infected area. Malignant tumor cells can also "metastasize" via the lymph
vessels as well.
http://swollenlymphglands.wordpress.com/
Copyright McGraw-Hill Companies
Copyright McGraw-Hill Companies
thymus
Bone marrow
STRUCTURE OF
LYMPHOID SYSTEM
COMPONENTS
END of Part 2
The End!