LAB|midterm Flashcards
1
Q
Primary aim of fixation
A
Primary aim: preserve the morphological and chemical integrity of the cell in as life-like manner.
2
Q
Secondary goal of fixation
A
harden and protect the tissue from the trauma of further handling
3
Q
fixed to structural proteins and thus rendered insoluble
A
Stabilizing proteins
4
Q
fixative becomes part of the tissue
A
Additive fixation
5
Q
fixative does not incorporate
A
Non-additive fixation
6
Q
Duration of fixation of buffered formalin
A
24 h
7
Q
Hydrogen Ion Concentration
A
pH 6 and 8
8
Q
Fixative According to composition
A
i. Simple Fixative
ii. Compound Fixatives
9
Q
types of Metallic Fixatives
A
- Mercuric Chloride
- Chromate Fixatives
- Lead Fixatives
- Heat
10
Q
made up of only one component substance.
A
Simple Fixative
11
Q
made up of two or more fixatives
A
Compound Fixative
12
Q
permits the general microscopic study of tissue structures
A
Microanatomical Fixatives
13
Q
preserve the specific parts and particular microscopic elements of the cell itself
A
Cytological
14
Q
preserve nuclear structures
A
Nuclear Fixative
15
Q
preserves cytoplasmic
A
Cytological Fixatives
16
Q
preserve chemical contents of cells and tissues
A
Histochemical Fixatives
17
Q
Use mercuric chloride and potassium dichromate
A
LIPID FIXATION
18
Q
fixation for phospholipids
A
Baker’s formol calcium
19
Q
CARBOHYDRATE FIXATION
A
Alcoholic formaldehyde
20
Q
PROTEIN FIXATION
A
Neutral buffered formol saline or formaldehyde
21
Q
GLYCOGEN FIXATION
A
Rossman’s fluid or absolute alcohol
22
Q
widely used ALDEHYDE FIXATIVES
A
Formaldehyde
23
Q
white precipitation
A
paraformaldehyde
24
Q
Removal of precipitate is addition of 10% methanol
A
Formaldehyde
25
- preserves enzymes and proteins
- fixation of CNS Tissues and General post-mortem tissues
10% Formol-Saline
26
- preservation of surgical, post-mortem and research specimens
- best fixative for iron-containing tissues
10% Neutral Buffered Formalin/Phosphate-Buffered Formalin
27
preserves human brain, pH 7
10% Neutral Buffered Formalin/Phosphate-Buffered Formalin
28
- routine post-mortem tissues
- excellent in silver reticulum methods
- fixes lipids, especially neutral fats and phospholipids
Formol-Corrosive (Formol Sublimate)
29
- immunoperoxidase studies on tissues
- used for rapid diagnosis
- good for preservation of glycogen and for micro- incineration
-used to fix sputum, since it coagulate mucus
Alcoholic Formalin (Gendre’s Fixative)
30
- two formaldehyde residues linked by 3C chains
- used for enzyme histochemistry and electron microscopy
- preserves plasma proteins
Glutaraldehyde
31
- most common metallic fixative
- Tissues fixed with mixtures containing mercuric chloride (except Susa) contain black precipitates of mercury.
- Routine fixative of choice for preservation of cell detail in tissue photography.
MERCURIC CHLORIDE
32
- Renal tissues, Fibrin, Connective tissues and muscles
- Black deposits may be removed by adding saturated iodine solution in 96% alcohol, the iodine being decolorized with absolute alcohol in the subsequent stages of dehydration.
MERCURIC CHLORIDE
33
- Mercuric Chloride + Glacial Acetic Acid
- fixing small pieces of liver, spleen, connective tissue and nuclei
- may act as mordant
Zenker’s Fluid
34
- fixative for pituitary gland, bone marrow and blood containing organs such as spleen and liver.
- preserves cytoplasmic granules
- Brown pigments are produced if tissues are allowed tomore than 24 hours.
Zenker-formol (Helly’s solution)
35
- tumor biopsies especially of the skin
Heidenhain’s Susa Solution
36
Lillie's B-5 Fixative
bone marrow biopsies
36
- used in 1-2% aqueous solution
- precipitates all proteins and adequately preserves carbohydrates.
Chromic Acid
36
- used in 3% aqueous solution
- preserves lipids
- preserves mitochondria
Potassium Dichromate
37
- Demonstration of chromatin, mitochondria, mitotic figures, Golgi bodies, RBC and colloid-containing tissues
- Prolonged fixation gives out black deposits and can be removed by running tap water.
Regard’s (Muller’s) Fluid
37
- study of early degenerative proceses and tissue necrosis
- demonstrates rickettsiae and other bacteria
- preserves myelin
Orth’s Fluid
37
- used in 4% aqueous solution
- recommended for acid mucopolysaccharides
- fixes connective tissue mucin
- forms insoluble lead carbonate due to prolonged standing which can be removed by filtration or adding acetic acid drop by drop
LEAD FIXATIVES
37
- Fixation of embryos and pituitary biopsies
- Preserving soft and delicate structures (endometrial curettings)
- yellow stain is useful for handling fragmentary biopsies.
- collagen, elastic connective tissues
Bouin’s Solution
38
- Yellow color may be removed by treatment with another acid dye or lithium carbonate
- excellent fixative for glycogen demonstration
- suitable for Aniline stains
PICRIC ACID FIXATIVES
39
- Fixative for glycogen
- Less messy than Bouin’s solution
Brasil’s Alcoholic Picroformal Fixative
40
- Precipitates chromosomes and chromatin materials
- Essential constituent of most common compound nuclear fixatives
GLACIAL ACETIC ACID
41
- Ideal for small tissue fragments
- Used as a fixative and dehydrating agent
ALCOHOLIC FIXATIVES
42
- fixing dry and wet smears, blood smears and bone marrow tissues
Methyl Alcohol
43
fixing touch preparations
Isopropyl Alcohol 95%
44
blood, tissue films and smears
Ethyl Alcohol
45
- fixing chromosomes, lymph node glands
- fix brain tissue for diagnosis of rabies
Carnoy’s Fluid
46
- fixing mucopolysaccharides and other proteins
Newcomer’s Fluid
46
- Pale yellow powder which dissolves in water to form strong oxidizing solution.
-fixes conjugated-fats and lipids permanently by making them insoluble during subsequent treatment with alcohol and xylene
-helps preserve cytoplasmic structure
-fixes myelin and peripheral nerves well
-fixes materials for ultrathin sectioning in electron
OSMIUM TETRAOXIDE (OSMIC ACID)
46
-an excellent fixative for nuclear structures
-permanently fixes fat
Flemming’s Solution
47
- Made up only of chromic and osmic acid
- Removal of acetic acid from the formula serves to improve the cytoplasmic detail of the cell
Flemming’s solution without acetic acid
48
- incorporated into compound fixatives
-precipitates proteins
-marked swelling effect on tissues serves to counteract shrinkage produced by other fixatives
-may be used as a weak decalcifying agent
TRICHLOROACETIC ACID
49
- Used at a cold temperature ranging from 5*C to 4*C
- Recommended for the study-of water diff8usible enzymes especially phosphatases and lipases
ACETONE
50
- Involves thermal coagulation of tissue protein for rapid diagnosis
- Employed for frozen tissue sections and bacteriologic smears
- Destroys RBC
- Dissolves starch and glycogen
HEAT FIXATION
51
- Process of replacing an already fixed tissue in a second fixative order
- Usually with 10% formalin or 10% formol saline as primary fixative
SECONDARY FIXATION
52
-form of secondary fixation whereby a primarily fixed tissue is placed in aqueous solution of 2.5- 3 % potassium dichromate for 24 hours to act as mordant for better staining effects
POST CHROMATIZATION
53
-process of removing excess fixative from the tissue after fixation in order to improve staining and remove artifacts from the tissues
WASHING-OUT
54
removes:
-excess chromates from tissues fixed in Kelly’s, Zenker’s, and Flemmings solutions
-excess formalin
-excess osmic acid
Tap water
55
used to wash out excess amount of picric acid (Bouin’s solution)
50-70% alcohol
56
used to remove excessive mercuric fixatives
Alcoholic iodine
57
Types of Aldehyde
1. Glutaraldehyde
2. Formaldehyde
58
- vary according to structural and chemical components of the cells to be studied
- may be done on fresh/preserved tissue
Fresh tissue examination
59
selected tissue is immersed in watch glass containing NSS then carefully dissected/separated and examined under the microscope.
Teasing/Dissociation
60
small pieces not more than 1 mm are placed in a slide and forcibly compressed with another slide or with a cover glass.
Squash Preparation/Crushing
61
examining sections of sediments, whereby cellular materials are spread lightly over a slide by means of wire loop or applicator.
Smear Preparation
62
two slides are used
Pull-Apart
63
zigzag line
Streaking
64
teasing mucous strands
Spreading
65
cells are transferred to the slide
Touch Preparation
66
Tissue is frozen with liquid nitrogen and a section is examined under the microscope.
Frozen Section
67
PROCESSING OF TISSUES
1. Fixation
2. Dehydration
3. Clearing
4. Infiltration (Impregnation) Embedding
5. Trimming
6. Section-Cutting
7.Staining
8. Mounting
9. Labelling
68
fixing or preserving fresh tissue for examination
Fixation
69
MAIN FACTORS INVOLVED IN FIXATION:
Temperature?
Formalin heated at 60C
70
MAIN FACTORS INVOLVED IN FIXATION:
Thickness of section?
2cm2 for light microscopy
71
MAIN FACTORS INVOLVED IN FIXATION:
Osmolality?
slightly hypertonic
72
PRACTICAL CONSIDERATIONS OF FIXATION:
1. Speed
2. Penetration
3. Volume
4. Duration of Fixation
73
Types of Lead Fixative
a. Picric Acid
b. Acetic Acid
c. Acetone
d. Alcohol
e. Osmium tetraoxide
74
What are the cytological fixatives
1. Nuclear fixative
2. Cytological Fixative
3. Histochemical Fixative
