Fixation and Fixatives Flashcards
fixation prevents?
degeneration, putrefaction, distortion, decomposition
defined the 2 basic mechanisms in fixation
ADDITIVE
- becomes part of the tissue by forming cross-links
- formalin, osmium tetroxide, mercury
NON-ADDITIVE
- not incorporated and stabilizes the tissue by removing tissue composition
- alcoholic fixatives
wrong fixation is?
irreversible
enumerate the main factors of fixations
- hydrogen ion concentration
- temperature
- thickness
- osmolality
- concentration
- duration of fixation
required temp for:
tissue processors -
electron M -
formalin -
tissues w/ TB -
tissue processors - 40C
electron M - 0-4C
formalin - 60C
tissues w/ TB - 100C
osmolality requirement
slightly hypertonic
concentration of formaldehyde and glutaraldehyde
formaldehyde 10%
glutaraldehyde 3%
duration of fixation for buffered formalin
2-6 hours
formalin can be washed out after fixation for?
24 hours
prolonged fixation may __ the tissues
shrinkage and hardening
volume of tissues
20x is the effective
enumerate the types of fixation accrdng to action and composition
simple and compound
SIMPLE FIXATIVES
- aldehyde
- metallic
- chromic acid
- lead fixatives
- picric acid
- acetic acid
- acetone
- alcohol
- osmium tetroxide
- heat
enumerate the metallic fixatives
- potassium dichromate
- mercuric chloride
- chromate
Carnoy’s fluid is composed of
glacial acetic acid, alcohol, chloroform
Susa’s fluid is composed of
mercuric chloride, sodium chloride, glacial acetic acid, and formaldehyde
permit the general microscopic study of tissue structures
microanatomical fixatives
preserve specific parts of particular microscopic elements and its ph. enumerate the fixatives.
cytological fixatives
- flemming’s w/out acetic acid
- orth’s fluid
- regaud
- kelly’s fluid
fixative that preserve nuclear structures and its pH. enumerate the 5.
nuclear fixatives = <4.6
- flemming’s
- carnoy
- bouin
- newcomer’s
- heidenhain susa
preserve cytoplasmic structures in lysosomes, mitochondria, golgi apparatus, and smooth and rough ER
cytoplasmic fixatives
fixative that uses ethanol and acetone which give best quantitative results using frozen tissues
precipitant fixatives
enumerate the histochemical fixatives
- formol salin 10%
- absolute ethyl alcohol
- acetone
- newcomer’s fluid
fixative for lipid preservation in cryostat sections
mercuric chloride and potassium dichromate
fixative used for phospholipids which contain amino acids
aldehyde
fixative for cholesterol for ultrastructural demonstration
digitonin
fixative for glycogen fixation
alcoholic fixatives
fixative for human skin
alcoholic formaldehyde
most commonly used fixative for amino acid histochemistry
neutral buffered formol saline or fomaldehyde vapor
fixative for preserving glycogen
Rossman’s fluid or cold absolute alcohol
can enhance better retention of glycogen
celloidin coating
used for improving the ultrastructural demonstration of lipids
imidazole osmium tetroide
fixative useful for electron cytochemistry
Karnovsky paraformaldehyde and glutaraldehyde
mixture with glutaraldehyde or formaldehyde useful for immersion fixation of surgical biopsies
acrolein
dilution ratio to make 10%
1:20
formaldehyde pH
7
recommended for central nervous tissue and postmortem tissue
10% formol saline
fixation time of 10% formol saline
24 hrs at 35C or 48hrs at 20-25
fixation time for 10% buffered formalin
4-24 hrs
recommended for post-mortem tissues and fixation time
formal-corrosive 3-24 hrs
composed of 95% ethyl alcohol saturated with picric acid, used for rapid diagnosis and micro-incineration technique
alcoholic formalin (genre’s)
fixative used to fix sputum
alcoholic formalin (genre’s)
used to fix small pieces of liver, spleen, connective tissue fibers, and nuclei
zenker’s fluid
fixation time of zenker’s
12-24 hrs
considered as microanatomical fixative since it used to fix pituitary gland, bone marrow, and blood containing organs such as spleen and liver
zenker-formol (helly’s solution)
main fixative for tumor biopsies especially in the skin, what is the fixation time
heidenhain’s susa 3-12 hrs
mainly used for bone marrow biopsies and the fixation time is 1-3 hrs
Lillie’s B5
used in 3% aqueous solution which preserves lipid and mitochondria
potassium dichromate
fixative recommended for demonstration of chromatin, mitochondria, mitotic figures, golgi bodies, BC, and colloid containing tissues. the fixation time is 12-48 hrs.
regaud’s (muller) fluid
used for early degenerative process and tissue necrosis. it also demonstrates rickettsia and other bacteria that preserves myelin better. what is also the fixation time
orth’s fluid
36-72 hrs
recommended for acid mucopolysaccharides that fixes connective tissue mucin
lead fixative
a stable fixative that dyes tissues producing yellow color and excellent for glycogen demonstration
picric acid
recommended fixation for embryos and pituitary biopsies. what is the fixation time?
bouin’s solution
6-24 hrs
fixes and precipitates chromosomes and chromatin materials
glacial acetic acid
excellent for fixing dry and wet specimens, blood smears, and bone marrow tissues
methyl alcohol
used for fixing touch preparation
isopropyl alcohol
the most rapid fixatives that is recommended for fixing chromosomes, lymph glands, and urgen biopsies
carnoy’s fluid
used to fix brain tissue for diagnosis of rabies and the fixation time is 1-3 hrs
carnoy’s fluid
recommended for fixing mucopolysaccharides and nuclear proteins
newcomer’s fluid
most common chrome-osmium acetic acid fixative used to fix nuclear structures and the fixation time is 24-48 hrs
flemming’s solution
recommended for study of water diffusable enzymes especially phosphatase and lipases
acetone
removes excess chromates, formalin, and osmic acid
tap water
wash out excess amount of bouin’s solution
50-70% alcohol
used to remove excessive mercuric fixatives
alcoholic iodine
factors affecting which slows down the fixation
- size and thickness
- presence of mucus
- presence of fat
- presence of blood
- cold temp
