Demonstration for Fibrin

Demonstration for Fibrin

1. factors can affect fibrin formation and structure

   • 1.Hereditary and acquired variations 2.environmtal conditions of polymerization process.
   • 1.hereditary and acquired variations
     • 1. different clot structures can arise from : fibrinogen  splice variants,  single nucleotide polymorphisms,  posttranslational  modifications to various parts of the molecule.
   • 2. environmtnat condition
     • 1. concentration of active thrombin: a) high thrombin levels:produce clots made up of  many thin fibers, branch point and small pores b)low thrombin levels:consist of thick fibers,fewer branch point and large pores
     • 2. Blood pH: pH 8-9:fine pH 6-6.5:coarse 3.ionic strength: Higher(in lung):fine Lower:placenta:coarse 4. enzymes
     • 5. concentration of fibrinogen: a)Low fibrinogen: clotting in static conditions ceases, when all fibrinogen is converted ti fibrin b)High fibrinogens: continual flow brings more fibrinogen, with thicker and bundled fibers.

2. Properties

   • 1. Eosinophilic 2.Monorefringent 3.weak autofluorescent 4.stains blue black in Mallory PTAH
   • 5. can digest by trypsin

3. Indication of fibrin

   • 1.tissue where there has tissue damage 2.exudate from acute inflammatory reactions
   • 3.Transudation of fluid and plasma proteins:out of damaged vessels 4.antemortem and postmortem thrombi

4. Fibrinoid

   • 1.regards as fibrin degradation product:FDP 2.it is eosinophic material 3.found in degenerative connective tissue 4.Found within vessel walls where undergo acute damage and as plugs in capillaries
   • properties
     • Some regards as a mixture of fibrin with other protein components of cytoplasm: 1.cannot be digested by trypsin 2.contains mucopolysaccharide and basic protein(PAS +++) 3.metachromatic(no metachromasia after digestied by enzymes)  
     • Special stain: SBB and ORO positive

5. How to fixed the tissue before the staining

   • Fixative:use formalin, (the best)formal sublimate
   • if using Masson type stains: Enhancement:more brilliant with 1. extended  mercuric chloride fixation. 2.thorough processing 3.decreasing*** 4.secondary fixation of sections
   • degreasing: 1.dewax section 2.treat with trichlorethylene 3.refix in absolute alcohol saturated with picric acid and mercuric chloride for 24 hours 4.down to water
   • advantages of decreasing: 1.remove lipid materials:inhibit penetration of aqueous fixatives and dyes 2.secondary fixation of the sections with a strongly precipitant fixative 

6. staining methods

   • Gram Wigart
     • 1.non specific 2.blue
   • PTAH
     • 1.more sensitive 2.stain young fibrins 3.blue black
   • Trichrome(Masson,MSB)**
     • 1. RBC,Fibrin:Red 2.old fibrin,collagen,ground substances:blue/green