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85 Cards in this Set
- Front
- Back
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Max tissue size
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3mm
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Cassette size
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4x3x0.5cm
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Longer fixation time
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Hepatitis
Tb HIV/aids Cjd |
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Quality control
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Monitors employee technique and maintenance of equipment
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Quality assurance
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Procedures will produce a valid and accurate outcome
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Effects of fixation
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Solidification
Hardening Optical differentiation Preservation Stainability |
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Good fixative is
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Must not shrink,swell,dissolve or distort
Kill bacteria or fungi Render enzymes inactive Make tissue resistant to subsequent treatments Make tissues readily colorable by suitable dyes |
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Causes of improper fixation
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Delay
Inadequate amount of fixative solution Fixative not suitable for type of tissue Prolonged fixation time |
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Compound fixative
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Several simple fixatives combined
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Simple fixative
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Used alone
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Coagulant/non coagulant
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Type of product formed by the reaction between the fixative and the protein in the tissue
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Coagulant
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Precipitating
Intolerant Fixative combines with protein to produce a coagulum Used alone Ie. Mercuric chloride, picric acid, ethanol, acetone, zinc |
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Non coagulant
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Non precipitating
Tolerant Fixative combines with protein and transforms the cytoplasm from a sol to a more life like gel Ie formalin or gluteraldehyde |
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Additive
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Fixative combines chemically with the tissue forming methylene bridges between the proteins
Ie formalin and gluteraldehyde |
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Non additive
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Do not form chemical bonds with the tissue but will break covalent and hydrogen bonds, changing the shape of the proteins
Ie alcohol or acetone |
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Non "a" words
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Additive fixatives
Formalin, mercury,osmium, gluteraldehyde |
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"a" words
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Non additives
Alcohol, acetone, acetic acid |
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Zapam
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Coagulants
Zinc,alcohol,picric acid,acetone,mercury |
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37-40% formaldehyde
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100%formalin
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Formaldehyde Artifact
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Paraformaldehyde
White ppt Removed by filtering Methanol is added to retard polymerization |
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Acid formaldehyde hematin
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If the pH drops below 6 formaldehyde breaks down to formic acid which reacts with the hgb molecules to form a formalin pigment
Afh is a brown ppt Treated with alcoholic picric acid Bifringent in polarized light |
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10% NBF CHO
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Glycogen trapped
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B5 CHO
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No reaction
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B5 effect on demonstration techniques
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Enhances staining on cytoplasm and nuclei Because of it's mordanting properties
Always a secondary fixative crüe to it's harshness |
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B5 ingredients
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Mecuric chloride
Sodium acetate Formaldehyde |
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10%NBF ingredients
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10 parts formalin
90 parts diluent |
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What leaves tissues more receptive to staining than any other fixative
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Mercury due to it's mordanting properties
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Mercury is...
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Never used alone
Inhibits freezing Used as a secondary fixative due to it's harshness Will leave a black mercury pigment |
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Dezankerization
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Used to remove mercury pigment
Alcoholic iodine and hypo ( sodium thiosulphate) are used |
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Zinc formalin ingredients
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Formaldehyde
Zinc sufate |
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Zinc formalin CHO
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Glycogen trapped
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Zinc formalin is used for
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Biopsy specimens
A replacement for mercury Enhances nuclear detail Good for immunos As a secondary fixative |
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Bouins ingredients
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Picric acid
Acetic acid Formaldehyde |
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Bouins CHO
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Preserves glycogen
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Bouins effect on demonstration
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Picric acid enhances trichrome stain
Glacial acetic acid lyses rbi and fixes nuclear proteins |
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Bouins is used for
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Gi biopsies
Endocrine tissue Glycogen studies Never use for kidney |
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Picric acid increases affinity for
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cytoplasmic elements
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Picric acid causes
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Excessive shrinking and must be used in a compound fixative
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Bouins works by
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Picric acid shrinks and softens
Glacial acetic acid swells Formaldehyde hardens Tolerance of formalin counteracts the intolerance of picric acid |
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Ethyl alcohol (ethanol) CHO
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Cold ethanol
Best fixative for glycogen Prevents glycogen streaming |
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Ethanol lipids
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Dissolves lipids
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Ethanol is used for
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Used in cytology
Best for cell fixatives Smears Glycogen Enzymes Cytology Urate crystals |
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Fixatives used for immunohistochemical
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10% NBF
Zinc formalin B5 Bouins |
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Frozen tissue is frozen at
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-70
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Quenching
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Snap freezing
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Gluteraldehyde CHO
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Glycogen are trapped
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Gluteraldehyde is used for
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Kidney biopsies
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Disinfectant fixative
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Gluteraldehyde
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Osmium tetroxide
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Secondary fixative
Best fixative for lipids and turns it black |
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Masking
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Reactive sites are not available due to over-fixation and cross linking
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Proteolytic digestion
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To expose antigen sites on protiens
Trypsin, pepsin, pronase |
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Hydroxyapatite
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Hydroxyapatite is a crystalline substance made of calcium, phosphate, hydroxyl ions
Forms small needle like crystals Forms a store of readily available calcium |
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Used for decalcification
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Hcl
EDTA Are the most common |
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Good decalcifier should
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Fast
Remove calcium without damaging the tissue Not interfere with staining reaction |
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Specimens that need decalcification
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Bone
Arteries Calcified soft tissue |
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Rate of decalcification
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Size
density Type Volume |
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Calcium salts are soluble at pH
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4.5
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End point decalcification is tested by
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Chemical testing(oxalate test)
X-Ray Physical testing (pricking) |
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Over decalcification results in
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Loss of nuclear staining
Loss of demonstratable iron Maceration of tissue |
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Nonpolar substance
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Wax
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Polar substance
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Water
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plastic point
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relates to the hardness of the wax
increase plastic point = decrease in bending |
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plastic additives
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increase the hardness and ability to produce thinner sections
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soft wax melting point
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45-50
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hard wax melting point
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60
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The faster the paraffin is cooled the _____the crystals formed are
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smaller
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clearance angle too great
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failure to ribbon
sections roll up washboard through tissue |
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clearance angle too small
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wrinkled sections
alternating thick and thin sections |
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chatter microscopic washboard is due to
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overdehydration
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disinfectant for the cryostat
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gluteraldehyde or formaldehyde fumes
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frozen section necessary
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muscle biopsy and lipids
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tissue frozen at
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-70 or liquid nitrogen
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tissue must warm up to ___ to be cut by the cryostat
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-20
because tissue would otherwise be too hard to cut |
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why are muscle biopsies snap frozen
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muscle is extremely prone to ice crystal formation. The faster the freezing the smaller the ice crystal.
must be frozen because routine processing would cause structural changes and loss cellular contents |
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cryostat thickness
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10-12um
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waterbath pickup
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debris on slide from previous tissues
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why are thymol or formalin are added to slide adhesives
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to prevent microorganism contamination
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primary fixative used for electron microscopy
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gluteraldehyde
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fixative for kidney biopsies
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gluteraldehyde
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secondary fixative for electron microscopy
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osmium tetroxide
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which fixative do you not use when doing a PAS
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gluteraldehyde
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how long does rapid processing take
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6 1/2 hours
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brain thickness
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6um
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routine thickness
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5um
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kidney biopsy thickness
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3um
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