FIXATION 3.0 Flashcards
It is a constituent of compound fixatives and it precipitates all proteins and adequately preserves CHO.
Chromic acid
It preserves lipids and mitochondria
Potassium Dichromate
This is recommended for the demonstration of : Chromatin, mitochondria, mitotic figures, Golgi bodies, RBC and colloid containing tissues
Regard’s (Muller’s) Fluid
What is the fixation time of Regard’s (Muller’s) Fluid?
12-48 hours
This fixative is recommended for early degenerative process, tissue necrosis and demonstration of Rickettsiae and bacteria
Orth’s fluid.
What is the fixation time of Orth’s fluid?
36 - 72 hours
Enumerate the Chromic Fixatives.
Chromic acid
Potassium Dichromate
Regard’s (Muller’s) fluid
Orth’s fluid
This is used in 4% aqueous solution of basic lead aerate and is recommended for acid mucopolysaccharides and connective tissue mucin.
Lead fixatives
Enumerate the metallic fixatives
Mercuric chloride
Chromate fixatives
Lead fixatives
This is normally used in a strong saturated aqueous solution (1%) and not in dry form. It is also used in dyes tissue yellow, and is an excellent fixative for glycogen demonstration.
Picric cid fixatives
This solution is recommended for embryos and pituitary biopsies
Bouin’s solution
This is better and less messy than Bouin’s solution and an excellent fixative for glycogen
Brasil’s Solution
Enumerate the Picric acid fixatives
Bouin’s solution
Brasil’s Solution
This is used in conjunction with the fixative to form a compound solution, solidified at 17’C .
Glacial Acetic ACid
The advantages of this fixative are:
- Fixes and precipitates nucleoproteins
- Causes tissues to swell
- Precipitates chromosome and chromosome material.
Glacial acetic acid
This rapidly denatures and precipitates proteins.
Alcoholic fixatives
Fix and preserve Glycogen, pigments, blood, tissue films and smear.
Absolute alcohol
This is ideal for small tissue fragments. Fixative and dehydrating agent, excellent for glycogen preservation and preserves nuclear stain.
Alcohol fixatives (70-100%)
This fixes dry and wet smear, blood smear and bone marrow tissue.
Methyl alcohol (100%)
This is used for touch preparations
Isopropyl alcohol (95%)
This is maybe used as a simple fixative.
Ethyl alcohol (70-100%)
What is the fixation time of ethyl alcohol (70-100%)?
18 - 24 hours
This is the most rapid fixative and can fix the tissue for 1 hour only. Fixes and dehydrates at the same time.
Carnoy’s fluid
This is used for urgent biopsies (5 hours) and brain tissue for diagnosis of rabies.
Carnoy’s fluid
What is the fixation time of Carnoy’s fluid?
1- 3 hours
This is pale yellow when dissolving into the water. However if it is in electron microscopy, the used stain is heavy metal.
Osmium tetroxide (Osmic acid)
its advantages are:
- Fixes conjugated-fats and lipids permanently
- Preserves cytoplasmic structures well
- Fixes myelin and peripheral nerves well
- Adequately fixes materials for ultra-thin sectioning
Osmium tetroxide (Osmic acid)
The disadvantage of this is that it deteriorates.
Flemming’s solution
This is the most common chrome-osmium acetic acid fixative, recommended for nuclear structures, permanently fixes fats.
Flemming’s solution
What is the fixation time of flemming’s solution?
24 - 48 hours
This is made up only of chromic and osmic, recommended for cytoplasmic structures (mitochondria).
Flemming’s SOlution w/out acetic acid.
Enumerate the osmium tetroxide (osmic acid) fixatives.
Flemming’s solution (w/ or w/out acetic acid)
This is sometimes incorporated into compound fixatives, precipitates proteins, Has a marked swelling effect and maybe used as a weak decalcifying agent.
Trichloroacetic acid
This is used at ice cold temperatures ranging from -5 to 4’C and is recommended for phosphates and lipases. It is used for fixing the brain and diagnosing rabies.
Acetone
This involves the thermal coagulation of tissue proteins, employed for frozen tissue sections and bacteriological smear and preserves nuclear and cytoplasmic detail.
Heat fixation
This is a pre-fixed undergone second fixative to improve the demonstration of particular substances.
Post mordanting/secondary fixation
This is for special staining technique.
Post-mordanting
This is for better staining.
Post chromatization 2.5 - 3% Potassium dichromate - mordant)
What is used to remove the excess?
Tap water
What do you call the removal of excess fixative?
Washing - out
What do you call the removal of pigment after fixation?
Washing out
How to remove the white ppt of formalin?
By adding 10% methanol
How to remove the brown/black precipitate of formalin?
Alkaline picrate (PIcric acid + 95% EA) OR
1% KOH in 80% alcohol
28% NH3 H20 + 70% ethyl alcohol is used to remove this.
Kardasewitsch’s
28%NH3 H2O, acetone + H2O2 (-wash in 70% alcohol)
Lillie’s
What is the solution used for the removal of picric acid?
Lenoir’s solution
What is used to wash out the mercuric fixative?
0.5% Iodine solution in 70% ethanol (5-10 minutes)
What is the decolorizer of Mercuric fixative?
5% Na thiosulfate
What decolorize the melanin?
KMnO4
What reduces the melanin?
Pyrogallic acid
What is used for bleaching and final removal of Melanin?
Hydrogen peroxide
What is used for the fixation for electron microscopy?
Aldehyde fixation:
A. Karnovsky’s paraformaldehyde - glutaraldehyde
B. Acrolein - glutaraldehyde / formaldehyde
What is used for the post fixation of Electron microscopy?
Acrolein
What is the pH for the post fixation of EM?
7.2 - 7.4
What is used fixative for enzyme histochemistry?
4% FORMALDEHYDE OR FORMOL-SALINE
What fixative is used for the frozen section of enzyme histochemistry?
Acetone or formaldehyde
What are the fixatives for smears?
Schaundinn’s
Ether-alcohol
Methanol