1What is the first and most critical step in histotechnology that terminates ongoing biochemical reactions, increases tissue strength, and inhibits bacterial and mold growth?
Fixation
2Preserving the morphologic and chemical integrity of a cell in a life-like manner?
Primary aim
3What process hardens and protects tissue from trauma during handling and makes it easier to cut and process for microscopy?
Secondary aim
4What are the objectives of fixation?
To Preserve the Tissue; To Prevent Breakdown of Cellular Elements; To Coagulate or Precipitate Protoplasmic Substances
5What is the mechanism in which a chemical constituent of the fixative is taken into and becomes part of the tissue?
Additive fixation
6What is the mechanism in which the fixing agent is not taken into the tissue but alters the tissue composition and stabilizes the tissue?
Non-additive fixation
7What is the traditional volume of fixative?
10 times
8What volume of fixative provides maximum effectiveness?
20 times
9What volume is used for Osmium tetroxide?
5–10 times
10What volume is used for Museum Preparation?
Not less than 50 times
11What pH range is best for fixation?
6–8
12What temperature is used for routine fixation?
40°C
13What temperature is used for electron microscopy?
0–4°C
14What is the thickness of section for Electron Microscopy?
1 to 2 mm²
15What is the thickness of section for Light Microscopy?
2 cm² and no more than 0.4 cm
16What osmolality usually gives the best results?
400–450 mOsm
17What concentration is widely used?
10% Formalin
18What concentration is ideal for Electron Microscopy?
3% Glutaraldehyde
19What can be used to cut down fixation time?
Heat, vacuum, agitation or microwave
20When should tissues be fixed to prevent autolysis or putrefaction?
Immediately after removal or death
21What type of fixative is made up of only one component?
Simple fixative
22What type of fixative is made up of two or more fixatives?
Compound fixative
23What type of fixative permits general microscopic study without altering the structural pattern and normal intercellular relationships?
Microanatomical fixative
24What fixatives must never contain Osmic acid because it inhibits hematoxylin?
Microanatomical fixative
25What type of fixative preserves specific parts and particular microscopic elements of the cell?
Cytological fixative
26What fixatives must NEVER contain glacial acetic acid, which destroys mitochondria and Golgi bodies?
Cytoplasmic fixatives
27What is the pH of Cytoplasmic Fixatives?
More than 4.6
28What fixatives contain glacial acetic acid as their primary component due to its affinity for nuclear chromatin?
Nuclear fixatives
29What is the pH of Nuclear Fixatives?
4.6 or less
30What type of cytological fixative preserves nuclear structures?
Nuclear fixative
31What type of cytological fixative preserves cytoplasmic structures?
Cytoplasmic fixative
32What type of fixative preserves the chemical constituents of cells and tissues?
Histochemical fixative
33What is the process of placing an already fixed tissue in a second fixative?
Secondary fixation
34What form of secondary fixation places primarily fixed tissue in 2.5–3% potassium dichromate for 24 hours?
Post-chromatization
35What is the process of removing excess fixative from tissue after fixation to improve staining and remove artifacts?
Washing out
36What removes excess chromates from tissues fixed in Kelly's, Zenker's, and Flemming's solutions, as well as excess formalin and osmic acid?
Tap water
37What removes excess amounts of picric acid from Bouin's solution?
50–70% Alcohol
38What removes excessive mercuric fixatives?
Alcoholic Iodine
39How thick should tissues be except lung edema?
Not more than 5 mm thick
40How thick may tissue slices be in lung edema?
1–2 cm
41What is the most commonly used chemical fixative, with 10% formalin being widely used?
Formaldehyde (Formalin)
42What should be injected before immersing the eyes in the fixative?
Formol alcohol
43What method involves hard tissues being washed out in running water overnight and immersed in 4% aqueous phenol solution for 1–3 days?
Lendrum's method
44What is usually buffered at pH 7.0 with phosphate buffer?
Formaldehyde
45What is the fixative of choice for immunohistochemistry and interphase Fluorescent in-Situ Hybridization?
Formaldehyde
46What is recommended for fixation of central nervous tissues and general post-mortem tissues for histochemical examination?
10% Formol-Saline
47What is recommended for preservation and storage of surgical, post-mortem, and research specimens?
10% Neutral-Buffered Formalin
48What is the best fixative for tissues containing iron pigments?
10% Neutral-Buffered Formalin
49What is recommended for routine post-mortem tissues?
Formol-Corrosive (Formol-Sublimate)
50What is the polymerized form of formaldehyde that depolymerizes back to formalin when heated?
Paraformaldehyde
51What fixative consists of 4% paraformaldehyde and 1% glutaraldehyde in 0.1M phosphate buffer?
Karnovsky's Fixative
52What fixative is made up of two formaldehyde residues linked by a three-carbon chain?
Glutaraldehyde
53What is an excellent fixative for dry and wet smears, blood smears, and bone marrow tissues?
100% Methyl Alcohol
54What alcohol is used for fixing touch preparations for special staining procedures such as Wright-Giemsa?
95% Isopropyl Alcohol
55What alcohol preserves nucleoproteins and nucleic acids and is used in histochemistry, especially enzyme studies?
70–100% Ethyl Alcohol
56What is the most rapid fixative and may be used for urgent biopsy specimens?
Carnoy's Fixative
57What solution is recommended for frozen sections and smears?
Clarke's Solution
58What fixative can be used for fixation or post-fixation of large fatty specimens, particularly breast tissue?
Alcoholic Formalin
59What fixative is sometimes used to fix diagnostic cryostat sections?
Formol-Acetic Alcohol