Talk:Draft 2016

Lymph Nodes

Lymph Node Anatomy

Lymph Node Anatomy
Location throughout the entire body - concentrated in axilla, groin, lung, gastrointestinal tract mesenteries Small (1 mm - 2 cm) encapsulated organ (diffuse lymphoid tissue - no capsule) Antigen transformed lymphocytes from the blood In lymph vessel pathways “filter” lymph Afferent - towards node (A - arrives at the node) Efferent - away from node (E - exits the node) Mesenteric lymph nodes

Lymph Node Functions

Lymph Node Functions
In lymph vessel pathways “filter” (surveillance) lymph Immune - detect infections from peripheral tissues skin, respiratory tract, gastrointestinal tract, etc. secondary lymphoid organ return extracellular fluid to circulation

Lymph Node Structure

Lymph Node Structure
Simplified structure	Lymphocyte (T and B) Traffic Enter from high endothelial venules (HEVs also called post-capillary venules) Spend 8 to 24 h in the lymph node interstitium. Enter a network of medullary sinuses. Drain from sinuses into efferent lymphatic vessels.
	Lymph pathway Afferent vessel Subcapsular sinus Paratrabecular sinus Medullary sinus Efferent vessel Watch T and B Lymphocytes Move   ‎‎Lymph Node 7 Page | Play  ‎‎Lymph Node 8 Page | Play

Lymph Node Histology

Lymph Node Histology

Connective Tissue Capsule - dense connective tissue (irregular CT, some adipocytes)) Trabeculae - dense connective tissue Reticular Tissue - Reticular cells and fibers, supporting meshwork (collagen type III) Reticular cell produces reticular fibers (collagen type III) and surrounds the fibers with its cytoplasm reticular fibres can also be produced by fibroblasts Subcapsular Sinus Follicle Germinal Centre (marginal sinus, continuation of trabecular sinus) Medullary Cords and Sinuses High Endothelial Venues Macrophages Lymph Node Cartoons: Detailed structure | Cartoon with Histology | Lymphocyte traffic | Simple structure | Simple node anatomy | Wiki node image | Internal structure | Mesenteric lymph node | Histology | Gallery | Lymph Node Development Links: Immunobiology - Figure 1.8. Organization of a lymph node

Diffuse Lymphatic Tissue

Tonsil and MALT

Alimentary canal, respiratory passage and urogenital tract.

• BALT - Bronchus Associated Lymphoid Tissue or GALT - Gut Associated Lymphatic Tissue
• Not enclosed by a connective tissue capsule
• Located in subepithelial tissue - lamina propria
• Diffuse lymphatic tissue + nodules
• Reactive - enlarge when activated (by antigen)

Lymphocytes

• travel to nodes and back again
• proliferation and differentiation

Lymph Nodules

• Organized concentrations of lymphocytes
  • No capsule, covered by epithelia
• Nodules are also the unit structure seen in a node
• Oval concentrations in meshwork of reticular cells

Nodule States

• Primary Nodule - Mainly small lymphocytes
• Secondary Nodule
  • Central pale region (germinal centre) - Effector cells and macrophages
  • Dark outer ring (small lymphocytes)

Gastrointestinal Tract

• Oropharynx - Tonsils
• Distal small intestine (ilieum) - Peyer’s Patches
• Appendix, cecum

Mucosal Associated Lymphoid Tissues

Anatomical location - Palatine (tonsils), Lingual and Pharyngeal ( adenoids ) Ring of oral adenoid tissue: anterior - lingual tonsil formed by the submucous adenoid collections. lateral - palatine tonsils and adenoid collections near the auditory tubes. posterior - pharyngeal tonsil on the posterior wall of the pharynx. between main masses are smaller collections of adenoid tissue.

Palatine Tonsils

• the "tonsils", lateral wall of oropharynx
• covered by stratified squamous epithelium
• numerous crypts (10-20) infolds of surface epithelium
• Afferent lymph vessels absent
• Efferent lymph vessels are present

Lingual Tonsils

• lamina propria root of tongue
• covered by stratified squamous epithelium
• salivary glands and skeletal muscle are directly adjacent

Pharyngeal Tonsils

• adenoids or nasopharyngeal tonsils, upper posterior part of throat
• covered by a pseudostratified ciliated epithelium with goblet cells

Peyer's Patch

• located in the ileum

Peyers patches (ileocolonoscopy)	Peyer's Patch (histology)	microfold cells or M-cells (transport gut lumen organisms and particles to immune cells across the epithelial barrier).

About Peyer's Patch

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation. Learn how the Peyer's Patches function in the Gut Mucosa immune function in this Nature Immunology Animation - Immunology in the Gut Mucosa Peyer's Patches are named after Johann Conrad Peyer (1653 – 1712) a Swiss anatomist who first described these specialised structures.