Chapter 11: Pigments, Minerals, and Cytoplasmic Granules Flashcards
Endogenous Pigment
A pigment formed within the body
Exogenous Pigment
A pigment formed externally which is then taken into the body
Carbon: black, often in lung and associated lymph nodes
Asbestos fibers: birefringent in lungs
Tattoo ink: skin and associated lymph nodes
Metals
Hematogenous Pigment
Pigments derived from the blood
Hemoglobin, Iron, Hemosiderin, Biliverdin (bile)
Anthracotic Pigment
black discoloration of bronchi from carbon pigment, usually due to smoke or coal inhalation
Endogenous, Nonhematogenous Pigment
Not derived from blood
Lipidic (lipofucsin and ceroid) and non-lipidic pigments (melanin)
Mineral
Metallic and non-metallic ions necessary for growth and other bodily functions
Calcium, ferric/cupric phosphate/carbonate
Silver, lead, copper, gold
Artifact
Deposited on tissue as a result of chemical action
Usually occur during processing due to certain fixatives
Mercury, Chrome, Formalin, Malarial
Hemoglobin
Protein in red blood cells for transporting oxygen
Stains with acid dyes such as eosin
May be pathologically found in recent hemorrhages or renal tubules after hemolysis
Hemosiderin
Storage form of iron in bone marrow and spleen, recycled for production of hemoglobin
Yellow to brown pigment
Large deposits are typically pathological since a majority of the iron is in use as RBCs
Bile (biliverdin)
Greenish bile pigment, component of Heme in RBCs
Reduced to bilirubin in the liver and is secreted as a component of bile
Demonstrated by oxidizing bilirubin (yellow-brown) to biliverdin (green)
Abnormal accumulations can result in jaundice (yellowing of the skin), and deposition in the Kupffer cells and hepatocytes
Hematoidin
Formed in tissues as a result of hemorrhage and reduced oxygen tension
A pigment similar to bilirubin that is also oxidized to biliverdin by bile-demonstrating techniques
Lifespan and degradation of erythrocytes
Lifespan of 120 days
Then split open by hemolysis or phagocytosed by macrophages in the spleen
Break down into Heme and Globin
Heme breaks down into iron and biliverdin (greenish bile pigment)
Function of Iron, where is it found?
Component of Red blood cells, also found in liver and bone marrow as hemosiderin
Hemachromatosis
Disease caused by excessive absorption of dietary iron characterized by excessive hemosiderin deposits
Can be differentiated from other yellow-brown pigments by the Prussian-Blue reaction
Bilirubin function and characteristics
(Yellow-brown) Reduced form of biliverdin (green bile pigment )
Melanocytes
Cells responsible for demonstration of melanin, contain dopa oxidase
Demonstrated by exposure of frozen sections to a buffered solution of dopa, melanin, or melanin-like pigment
Melanin
Derived from tyrosine and is characteristically a brown-black pigment
Summary of melanin production
tyrosine is oxidized to dopa which is oxidized to melanin
What is lipofucsin, where is it found?
A lipidic pigment indicating “wear and tear” which collects in more permanent tissues such as the heart, liver, and neurons
Yellow-brown and stains with Oil Red O, Sudan Black B, and PAS
What is ceroid, where is it found?
A lipid pigment seen in hepatocytes and macrophages with liver cirrhosis
Yellow-brown, stains with Oil Red O, Sudan Black B, and PAS.
Can be differentiated from lipofucsin using acid fast stain (ceroid is acid-fast positive)
Where are three places melanin is found in the body?
eyes, hair, skin
Method for bleaching melanin pigment
Expose to an oxidizing agent, such as 10% hydrogen peroxide or 0.25% potassium permanganate followed by oxalic acid (to clear sections of color)
This is to help retain cell detail when melanin pigment is present in large quantities
Preferred fixative for minerals
Formalin because metallic fixatives (mercury, chrome) would leave artifacts in the tissue
What are urate crystals, where are they found?
Urate crystals (sodium/uric acid deposits) are found in tissue and joints of people suffering from gout They are an endogenous deposit, originating inside the body They must be fixed in methanol (non-aqueous) because they are water soluble; are birefringent (polarizing microscopy), and can be demonstrated with argentaffin methenamine silver techniques
Argentaffin vs Argyrophilic silver reactions
Argyrophilic cells can be impregnated with silver, but require an external reducer (chemical or light) to demonstrate metallic silver. Can only be demonstrated with Argyrophil techniques.
Argentaffin cells can be impregnated with silver and reduce those ions to their visible metallic form. Can be demonstrated wit both argentaffin and argyrophil techniques
Silver stains are used to demonstrate cytoplasmic granules
Prussian Blue Purpose
Detection of ferric iron in tissues
Typically found in small amounts in the bone marrow and spleen
Excess hemosiderin (idiopathic hemochromatosis can lead to organ failure and death
Prussian Blue Principle
Detects the ferric iron (Fe3+) in loosely bound protein complexes (such as hemosiderin)
Strongly bound iron in hemoglobin will not react with Prussian Blue
Iron ions in the tissue react with acidic potassium ferrocyanide to form Prussian-Blue
Prussian Blue Preferred Fixative
Alcohol or 10% NBF
Prussian Blue Basic Procedure
- Deparaffinize, hydrate (use non-metallic forceps)
- Place slides in potassium-ferrocyanide and hydrochloric acid solution for 20 minutes
- Wash in distilled water
- Counterstain in nuclear fast red
- Rinse thoroughly in tap water to prevent cloudiness
- Dehydrate, clear, coverslip
Prussian Blue Results
Nuclei and hemofuchsin: bright red
Hemosiderin (iron): blue
Background: pink
Prussian Blue Technical Notes
Staining containers must be clean or residual iron will cause diffuse background staining
Acid decalcifiers for bone can dissolve iron; use 3% or 5% acetic acid or formic acid to preserve iron
Excess nuclear fast red must be thoroughly washed out to prevent cloudiness when placed in alcohol dehydrant
Turnbull Blue Purpose
Detection of Ferrous iron Fe2+ (very toxic) in tissue, rapidly converted to ferric form
Turnbull Blue Principle
Ferrous iron in the tissue reacts with acidic potassium-ferricyanide to form Turnbull blue
Turnbull Blue Preferred Fixative
alcohol or 10% NBF
Turnbull Blue Basic Procedure
- Deparaffinize, hydrate (use non-metallic forceps)
- Place slides in freshly prepared ferricyanide staining solution
- Wash in acetic acid
- Counterstain in nuclear fast red
- Rinse thoroughly in distilled water to prevent cloudiness
- Dehydrate, clear, coverslip
Turnbull Blue Results
Ferrous iron: blue
Background: pink-red