Pigments

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Def:-
It is deposition of abnormal material either techniqually or pathologically or physiologically.
Classify:-
1- Artifacts
2- Endogenous
3- Exogenous.
1-Artifacts:-
Def:
Deposition of compound as result of chemical substance .
Type:
1- formalin pigment.
It is brown pigment produced by fixation of tissue with acid solution of formaldehyde(acid formaldehyde haematin).
acid formaldehyde react with haematin found in tissue to give acid formaldehyde haematin.
Preventation:-
To prevent should be used buffered PH7(Na2HPO4. NaH2PO4)
To removed add Saturated Alcoholic picric acid for 5-10 minute.


2-Mercry Cholride pigment:-
It easily demonstrated because distributed over section like having sharper needle
. Preventation:-
Cann,t prevent it , but if form can be removed by Gram iodine or lugal iodine or add iodine to 70 alcohol during dehydration then treated the section by Na thiosulphate to remove iodine colour.


3- Dichromate pigment:-
Are brown or black granules found when fix tissue by K dichromate as result lower oxide
Preventation:-
Washing under tap water.
Remove by 1% of acid alcohol to remove lower oxide or washing under tap water to 10 minute.


4-Stain precipitate:-
Any satin contain alcohol precipitate due evaporation especially under heating.
Preventation:-
Can be prevent by but section in coplen jar and heat inside the oven.


5-Malaria pigment:-
This result of remains of malaria parasite inside red cell .
Prevent:-remove by % 1 acid alcohol or saturated alcoholic picric acid.
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