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Questions and Answers
What is the purpose of 10% Formol-saline fixative?
What is the purpose of 10% Formol-saline fixative?
What is an advantage of using 10% Formol-saline fixative?
What is an advantage of using 10% Formol-saline fixative?
What is a disadvantage associated with the use of 10% Formol-saline fixative?
What is a disadvantage associated with the use of 10% Formol-saline fixative?
Which type of tissue is 10% Formol-saline fixative specifically recommended for fixing?
Which type of tissue is 10% Formol-saline fixative specifically recommended for fixing?
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What effect does 70% alcohol have when used in combination with 10% Formol-saline fixative?
What effect does 70% alcohol have when used in combination with 10% Formol-saline fixative?
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What happens to large specimens fixed with 10% Formol-saline for a long time?
What happens to large specimens fixed with 10% Formol-saline for a long time?
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What is the fixation time for Formol-corrosive/ Formol-sublimate fixative?
What is the fixation time for Formol-corrosive/ Formol-sublimate fixative?
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Which of the following is an advantage of Formol-corrosive/ Formol-sublimate fixative?
Which of the following is an advantage of Formol-corrosive/ Formol-sublimate fixative?
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What is a disadvantage of using Formol-corrosive/ Formol-sublimate fixative?
What is a disadvantage of using Formol-corrosive/ Formol-sublimate fixative?
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Which fixative forms mercuric chloride deposits and inhibits decalcification determination?
Which fixative forms mercuric chloride deposits and inhibits decalcification determination?
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What does high mercuric chloride content in a fixative cause after treatment?
What does high mercuric chloride content in a fixative cause after treatment?
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Which fixative is intolerant and corrosive to metals?
Which fixative is intolerant and corrosive to metals?
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What is the name of the fixative which contains formaldehyde and alcohol?
What is the name of the fixative which contains formaldehyde and alcohol?
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Which of the following fixatives is recommended for preservation and storage of surgical, post-mortem, and research specimens?
Which of the following fixatives is recommended for preservation and storage of surgical, post-mortem, and research specimens?
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Which fixative is known for preventing the precipitation of acid formalin pigments on post-mortem tissues?
Which fixative is known for preventing the precipitation of acid formalin pigments on post-mortem tissues?
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What is the disadvantage of using Neutral buffered formalin as a fixative?
What is the disadvantage of using Neutral buffered formalin as a fixative?
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Which fixative shows reduced positivity of Mucin to PAS?
Which fixative shows reduced positivity of Mucin to PAS?
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Which fixative is mentioned to be similar to formol-saline and recommended for tissues with iron-pigments and elastic fibers?
Which fixative is mentioned to be similar to formol-saline and recommended for tissues with iron-pigments and elastic fibers?
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Study Notes
Aldehyde Fixatives
- Formaldehyde 10% is also known as Formalin 10%, Formol-saline 10%, Neutral buffered formalin, Formal-corrosive, Formol alcohol, Acetic alcohol formaldehyde, Formol ammonium bromide, 10% formol calcium, and Formol sucrose.
Formol-Corrosive/Formol-Sublimate
- Mercuric chloride is also known as corrosive sublimate.
- It is recommended for routine post-mortem tissues.
- It is valuable for secondary fixation following primary fixation in 10% formalin variants.
- Fixation time is 3-24 hours.
- Advantages: rapidly penetrates small pieces of tissue, produces minimum shrinkage and hardening, excellent for many staining procedures, brightens cytoplasmic and metachromatic stains, and preserves cytological structures and blood cells.
- Disadvantages: penetration is slow, forms mercuric chloride deposit, does not allow frozen tissue sections to be made, inhibits the determination of the extent of tissue decalcification, is intolerant to fixative, and corrodes metal.
10% Neutral Buffered Formalin/Phosphate-Buffered Formalin (pH 7)
- It is desirable compared to 10% formalin.
- It is recommended for preservation and storage of surgical, post-mortem, and research specimens.
- Buffer: phosphate.
- Fixation time: 4-24 hours.
- Advantages: similar to formol-saline, prevents precipitation of acid formalin pigments on post-mortem tissue, and best fixative for tissues with iron-pigments and for elastic fibers.
- Disadvantages: preparation is time-consuming, reduces positivity of mucin to PAS, reduces reactivity of myelin to Weigert's Iron Hematoxylin Stain, and is inert towards lipids.
10% Formol-Saline
- It is a simple microanatomical fixative composed of 10% formalin + NaCl (maintains osmolarity).
- It is recommended for fixation of central nervous tissue, general post-mortem tissues for histochemical exam, and fixation time is 24 hours at 35°C (95°F); 48 hours at 20-25°C (65-77°F).
- Advantages: penetrates and fixes tissues evenly, preserves microanatomic and cytologic details, large specimens may be fixed for a long time (must change the solution every 3 months), preserves enzymes and nucleoproteins, demonstrates fats and mucins, ideal for most staining techniques (silver impregnation), and + 70% alcohol = restoration of natural tissue color.
- Disadvantages: slow fixative (>24 hours), tissues tend to shrink during alcohol dehydration (solution: secondary fixation), and metachromatic reaction of amyloid is reduced.
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Description
Explore the properties and recommended uses of various aldehyde fixatives commonly used in histology, such as Formaldehyde 10%, Formol-saline 10%, and Neutral buffered formalin. Understand the fixation times and temperatures for different tissues and samples.
