Changes

* Occurs when the organism causing the initial necrosis in the tissue is capable of attracting and killing large numbers of [[Neutrophils|neutrophils]]]].  

* Occurs when the organism causing the initial necrosis in the tissue is capable of attracting and killing large numbers of [[Neutrophils|neutrophils]]]].  

** I.e the '''pyogenic bacteria'''.

** I.e the '''pyogenic bacteria'''.

* [[Neutrophils - WikiBlood|Neutrophils]] release proteolytic enzymes when they die.

* [[Neutrophils|Neutrophils]] release proteolytic enzymes when they die.

** These digest the dead tissue and also more incoming [[Neutrophils - WikiBlood|neutrophils]].

** These digest the dead tissue and also more incoming [[Neutrophils|neutrophils]].

*** The liquid formed is called '''pus'''.

*** The liquid formed is called '''pus'''.

* Pus is mainly composed of dead and dying [[Neutrophils - WikiBlood|neutrophils]] .

* Pus is mainly composed of dead and dying [[Neutrophils|neutrophils]] .

** Also contains the remnants of the necrotic tissue cells.

** Also contains the remnants of the necrotic tissue cells.

* Although in favourable cases the [[Neutrophils - WikiBlood|neutrophils]] may eventually kill the organisms, in most cases the organisms persist, producing more pus.  

* Although in favourable cases the [[Neutrophils|neutrophils]] may eventually kill the organisms, in most cases the organisms persist, producing more pus.  

** Produces an expanding sphere of pus known as an [[Acute Inflammation - Pathology#Purulent|'''abscess''']].  

** Produces an expanding sphere of pus known as an [[Acute Inflammation - Pathology#Purulent|'''abscess''']].  

*** If the abscess is near to the skin and pressure becomes sufficient after build up, it will burst.

*** If the abscess is near to the skin and pressure becomes sufficient after build up, it will burst.

=====Histological Appearance of an Abscess=====

=====Histological Appearance of an Abscess=====

* The necrotic area shows varying stages of degeneration of the [[Neutrophils - WikiBlood|neutrophils]].

* The necrotic area shows varying stages of degeneration of the [[Neutrophils|neutrophils]].

** Ranges from nearly normal [[Neutrophils - WikiBlood|neutrophils]], through pyknosis, karyorrhexis and karyolysis, finally to a homogenous, structureless, mixture of remnants.

** Ranges from nearly normal [[Neutrophils|neutrophils]], through pyknosis, karyorrhexis and karyolysis, finally to a homogenous, structureless, mixture of remnants.

*** Stains faintly bluish.

*** Stains faintly bluish.

* There is a host inflammatory response directed against the sphere of pus as it is forming.

* There is a host inflammatory response directed against the sphere of pus as it is forming.

** Results in a capsule of fibrous tissue which has many blood vessels on its inner surface.

** Results in a capsule of fibrous tissue which has many blood vessels on its inner surface.

*** Allows the transport of the vast number of [[Neutrophils - WikiBlood|neutrophils]] into the necrotic centre.  

*** Allows the transport of the vast number of [[Neutrophils|neutrophils]] into the necrotic centre.  

*** Known as the 'pyogenic membrane'.  

*** Known as the 'pyogenic membrane'.  

*** Can be viewed following abscess discharge as a crater that has a reddish, somewhat ragged lining.  

*** Can be viewed following abscess discharge as a crater that has a reddish, somewhat ragged lining.