Difference between revisions of "Category:Lymph Nodes"

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==Role of the Lymph Node in Inflammation==
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[[Category:Secondary Lymphoid Tissue|A]]
''Back to [[Inflammation - Pathology]]
 
*  Antigenic material is transported in phagocytes via the tissue lymphatics to the local lymph node.
 
* In the subcapsular sinusoids of the lymph node, antigens are exposed to the reticular cell macrophages.
 
** These macrophages form a meshwork around the subcapsular, cortical and medullary sinusoids.
 
** These reticular cells present the antigen to the appropriate lymphocyte population.
 
*** To B-cells in the follicular centres
 
*** To T-cells in the parafollicular areas.
 
* When stimulated by antigen presentation, the respective areas undergo an increase in size by hperplasia.
 
** The lymphocytes produced later leave the lymph node to seek out the source of the antigen in the damaged portion.
 
* Bacteria surviving the initial local inflammatory reaction also travel to the lymph node.
 
** Travel either in macrophages or as a bacteraemia/septicaemia.
 
**  In the lymph node, many bacteria are trapped, degraded and killed, or  exposed to antibody produced by plasma cells in the medullary area.
 
** Bacteria set up an acute inflammatory response in the lymph node.
 
*** If they are pyogenic, baceria can produce abscessation in the lymph node.
 
**** E. g. Strangles.
 
***** An upper respiratory tract pathogen in the horse.
 
***** Abscesses in the cervical lymph nodes burst to the exterior.
 
***** Abscesses in the retropharyngeal node burst into the pharynx
 
***** Infection is usually localised to the head and neck, but can spread to cause abscessation elsewhere in the body.
 
 
 
===Bacteraemia===
 
 
 
* Bacteria may continue through the lymph nodes and circulate in the blood.
 
* These are generally cleared from the blood by other organs containing phagocytes.
 
** E.g. the [[Liver - Anatomy & Physiology|liver]], [[Spleen - Anatomy & Physiology|spleen]] and lungs.
 
* There are species differences in the ability to remove bacteria.
 
** In most species, the majority of clearance is carried out by the [[Liver - Anatomy & Physiology|liver]] and spleen.
 
** However, in the pig, the lung removes 60-80% of such bacteria.
 
 
 
===Septicaemia===
 
* Septicaemia is a condition where there are highly pathogenic bacteria circulating and rapidly multiplying in the blood.
 
** Accompanied by severe signs of clinical illness due to the liberation of bacterial toxins.
 
*** High fever
 
*** Rapid respiration
 
*** Shock
 
** Can result in the death of the animal.
 
====Gross Appearance====
 
* The lymph nodes, [[Liver - Anatomy & Physiology|liver]] and spleen are very hyperaemic and swollen.
 
 
 
====Histological Appearance====
 
* Capillaries in tissues taken immediately after death show bacteria in their lumens.
 
 
 
==Diseases Involving Reactive Nodes==
 
===Parasitic Diseases===
 
====bovine parasitic bronchitis====
 
====ostertagiasis====
 
====fascioliasis====
 
===Bacterial Diseases===
 
====clostridial====
 
 
 
==Diseases Involving Both Reactive Nodes and Lymphadenitis==
 
===[[Tuberculosis - Cattle]]===
 
 
 
===viz. brucellosis and Johne's disease===
 
* chronicity is caused by persistence of intacellular bacteria in lymph node macrophages
 
* Type IV hypersensitivity, but does not result in visible necrosis as in TB
 
 
 
===Johne's disease===
 
===Actinobacillosis===
 
===Actinomycosis===
 
===Equine strangles===
 
* acute inflammation
 
* produce pyogenic or necrotic foci in the drainage nodes
 
* involves submaxillary nodes
 
 
 
===Streptococcal adenitis or head gland disease===
 
* dogs
 
* acute inflammation as in above
 
 
 
==Diseases Parasitising the Lymphocytes==
 
*organism grows in the lymphocytes and ruptures them
 
*if large infecting dose
 
:- may be rapidly fatal since animal may no tb e able to mount an immunological attack
 
*if smaller infecting dose
 
:- loss of mature lymphocytes causes a dramatic stimulation of the remaining lymphocyte precursors
 
:- node hyperplasia follows
 
:- competition between lymphocytolysis by the organism and lymphocyte production by the nodes
 
:- clinically
 
::- may be swelling of the node at one stage and reduction in size at another
 
 
 
===canine distemper===
 
*virus
 
===swine fever===
 
*virus
 
===bovine east coast fever===
 
*protozoan
 
 
 
===[[Leishmania|Leishmaniasis in the dog]]===
 
 
 
==Other Lymphadenopathy==
 
===Lymph node pigmentation===
 
*Lungs
 
:- anthracosis
 
::- carbon derived from soot finds its way to the local nodes in macrophages
 
*Skin
 
:- dermatopathic lymphadenopathy or melanic reticulosis
 
::- in pigmented animals, especially black dogs
 
::- chronic inflammatory skin conditions lead to melanin deposition in hyperplastic nodules
 
:-  also occurs in nodes draining skin melanomas where the pigment may be  the result of skin ulceration or secondary tumour deposit
 
::- these two should not be confused since the prognosis is very different following surgery
 
 
 
===Emphysema===
 
*interstitial emphysema
 
:- common in cases of dyspnoea
 
:- more commonly affects bovine lung
 
::- due to well developed pulmonary lobulation and hence much loose interstitial lung tissue
 
*collection of gas bubbles in bronchial and mediastinal lymph nodes
 
:- gas travels to these nodes after gaining entry to the many lymphatic vessels present in the interstitial tissue
 
 
 
===Neoplasia===
 
* Primary tumours
 
** Lymphosarcoma (lymphoma)
 
:-  of lymphoid cells with lymph node enlargement
 
:- smooth, pale hemogenous but may have areas of necrosis
 
:- may cause [[Parathyroid Glands - Pathology#Pseudo-Hyperparathyroidism|pseudo-hyperparathyroidism]]
 
* Secondary tumours
 
:- nodes often involved in the spread of tumours by extension or metastasis
 
:- usually carcinomas
 
 
 
==Haemal Lymph Nodes==
 
*ruminants only
 
*small; dark red/brown
 
*develop during foetal life
 
:- lymph node primordia which lose their lymph vessles
 
:- receive all cells and antigen from the BLOOD
 
*functional significance unclear
 
*probably respond to blood-borne antigen
 
 
 
[[Category:Inflammation]]
 

Latest revision as of 14:39, 24 February 2011

Pages in category "Lymph Nodes"

The following 5 pages are in this category, out of 5 total.