Transcript 8_tissues and organs hx

Organization of the lymphoid
organs and tissues
LYMPHOID ORGANS
Primary lymphoid organs:
- Bone marrow
- Thymus
Secondary lymphoid organs:
- Spleen
- Lymphatic vessels
- Lymph nodes
- Adenoids and tonsils
- MALT (Mucosal Associated Lymphoid Tissue)
GALT (Gut Associated Lymphoid Tissue)
BALT (Bronchus Associated Lymphoid Tissue)
SALT (Skin Associated Lymphoid Tissue)
NALT (Nasal Associated Lymphoid Tissue)
Primary lymphoid organs
Bone marrow
GENERATION OF BLOOD CELLS DURING LIFE SPAN
BEFORE BIRTH
AFTER BIRTH
Cell number (%)
Yolk sac
80
Flat bones
Liver
60
40
Spleen
20
Tubular bones
0
0 1 2 3 4 5 6 7 8 9
10
20
30
40
50
60
70
years
months
BIRTH
BONE MARROW
TRANSPLANTATION
Structure of the bone marrow
Bone marrow
CELL TYPES OF THE BONE MARROW
Stem cells
Osteoblasts
Stromal cells
BONE
csont
Osteoclasts
B-cell precursors
Progenitors
Precursors
Dendritic cell
Central
centrális
sinus
sinus
Blood circulation
Unspecialized stem cells with unlimited proliferating capacity
SELF RENEWAL AND POTENCY OF DIFFERENTIATION OF STEM CELLS
HSC – assymetric cell division
self renewal
cell differentiation
Self renewal
Differentiation to
any precursor cell
BONE MARROW
HSC
MYELOID
PRECURSOR
HEMATOPOIETIC STEM CELL
LYMPHOID
PRECURSOR
BLOOD
BLOOD
DC
monocyte mast neutrophil
TISSUES
DC
THYMUS
macrophage mast
B-cell
NK-cell
T-cell
LYMPHOID TISSUES
B-cell
T-cell
Primary lymphoid organs
Thymus
STRUCTURE OF THE THYMUS
Thymocytes from the bone marrow arrive at the thymus and mature into naive T cells
Capsule
Septum
Blood
circulation
Epithelial cells
Thymocytes
Dendritic cell
Macrophage
Mature naive T- lymphocytes
Hassall’s corpuscle
THYMUS INVOLUTION
PERIPHERAL (or SECONDARY)
LYMPHOID ORGANS
The innitation of adaptive
immune response
• Lymph nodes
• Spleen
• Epithelial cell – associated lymphoid tissues
MALT (Mucosal Associated Lymphoid Tissue)
GALT (Gut Associated Lymphoid Tissue)
BALT (Bronchus Associated Lymphoid Tissue)
SALT (Skin Associated Lymphoid Tissue)
NALT (Nasal Associated Lymphoid Tissue)
Organization (levels) of immunocytes
Diffuse cells
Follicle
Patch
organ
LYMPHATIC CIRCULATION SYSTEM
Lymphatic vessels
Lymph circulates to the lymph node via afferent lymphatic vessels and then leaves the
lymph node via the efferent lymphatic vessels towards either a more central lymph
node or ultimately for drainage into a central venous subclavian blood vessel.
Lymph node
HOMING OF LYMPHOCYTES
IN LYMPH NODES
Naive lymphocytes enter lymph nodes via HEV
B cells are recruited to HEV from the blood by
chemokine secreted by stromal cells
SPLEEN
SPLEEN
The spleen filters the
blood and serves as
a secondary
lymphoid organ
Spleen
Lymphocyte aggregations are
similar to the lymph node only
that cells and pathogens enter
from the blood
Red pulp- filters the blood; from
antigens, microorganisms and
worn-out RBCs
STRUCTURE OF THE SPLEEN
White pulp
NO LYMPHOID CIRCULATION
Filtration of blood borne antigens
Spleen white pulp
Transverse section
Marginal sinus
B cell corona
Red pulp
Germinal centre
Marginal zone
Periarteriolar lymphocytic
sheath (PALS) – T cell area
Central arteriole
PERIPHERAL LYMPHOID
ORGANS
Sites of lymphocyte activation
and differentiation
Lymph nodes
Spleen
Epithelial cell – associated lymphoid tissues
MALT (Mucosal Associated Lymphoid Tissue)
GALT (Gut Associated Lymphoid Tissue)
BALT (Bronchus Associated Lymphoid Tissue)
SALT (Skin Associated Lymphoid Tissue)
NALT (Nasal Associated Lymphoid Tissue)
Secondary lymphatic tissues
MALT
 Lymphatic tissues that are more diffused are generally known as MALT (Mucosa
associated lymphatic tissue). Similar microanatomy as the lymph nodes and spleen
• Most of the pathogens get into human body through mucosa
• A thin, huge surface, dinamic structure
• Intense and active immune surveillance mechanisms ensure the protection
• Goblet cell produced mucus contains glycoproteins, proteoglycans, special enzymes
• Anti microbial peptides produced mostly by Panath cells provide biological defense
mechanism against infection
• Most of the lymphocyte reside around the mucosal surface
GUT-ASSOCIATED LYMPHOID TISSUES
Small intestine
Large intestine
GUT-ASSOCIATED LYMPHOID TISSUES
Peyer’s patches 5-100 follicles forming a dome structure
M-cells: microfold cells --- no glycocalyx – antigen uptake
GALT
• The Lamina propria contains lymphatic tissue
underlying the gastrointestinal tract connective tissue
• The small intestine contains lymphoid nodules; the
Peyer’s patches and isolated lymphoid follicles.
• Pathogens are delivered across the mucosa to APCs by
specialized mucosal epithelial cells are called the M cells
(microfold cells).
Transport of antigens via M cells
Dendritic cells of the lamina propria are able to capture antigens
by sampling the gut lumen directly outside the Peyer’s patches
Intra-epithelial lymphocytes