GPHT LAB - Fixation Handouts Flashcards
grp of fixatives satisfactory for routine paraffin sections, frozen sections, and for EM
aldehyde fixatives
gas produced by oxidation of MetOH
formaldehyde
HCHO soluble in water to the extent of ___ by weight
40%
powerful RA, used in the make up of Helly’s fluid
formaldehyde
purest solution (how many percent) of formaldehyde
40%
routine formalin sol’n how many percent
10%
how to prep routine formalin sol’n
10 ml strong HCHO
90 ml H20 or saline
dilution of routine formalin sol’n
1:10
usual fixation time of HCHO
12-24 hrs
often becomes turbid
commercial HCHO
why does commercial HCHO become turbid after prolonged storage
due to formation of paraformaldehyde which is caused by HCHO polarization
presence does not impair fixing qualities of HCHO
paraformaldehyde
removal of formalin pigments methods (3)
Kardasewitsch’s
Lillie’s
Picric Acid Method
what method of removal of formalin pigments
section placed for 5 min - 2 hrs in 70% EtOH, 28% NH3 water
Kardasewitsch’s
what method of removal of formalin pigments
section placed for 1-5 min in acetone, 3 vol H2O2, 28% NH3 H20, rinsed in 70% EtOH
Lillie’s
section placed for 5 min - 2 hrs in std solution of picric acid
washed in running water for 11-15 min
picric acid method
aldehyde MW 100 or 2 formaldehyde residues linked by a striaght 3C chains
glutaraldehyde
best used for small fragments and small needle biopsies
2.5% glutaraldehyde
for larger tissue not exceeding 4mm in thickness, for 12-24 hrs at RT
4% solution of glutaraldehyde
polymer of formaldehyde, white powder
paraformaldehyde
used in a 4% strength at 4c
paraformaldehyde
frequently used in saturated soln
mercuric chloride
solubility of HgCl2 in water at RT
7%
in removing mercuric chloride granules, sections are placed in alcoholic iodine for 1-2 min. give exact composition of alcoholic iodine
0.5 ml iodine in 100 ml 70% EtOH
in removing mercuric chloride granules, sections are rinsed in water and placed in _____ for 1-2 min to remove iodine
5% sodium thiosulfate (hypo) solution
used in 1-2% aqueous solution
chromate fixatives
strong OA, should not combine with RA like alcohol and formalin
chromate fixatives
used in 3% aq. sol’n
potassium dichromate
strong fixative for certain lipids
potassium dichromate
used in 4% aq solution
lead fixatives
used in strong or sat. solution
picric acid fixative
picric acid chemical name
2,4,6-trinitrophenol
how many grams Picric acid will dissolve in 100 ml of dist. H20 and at what temperature
1.7 g
15C
To remove picric acid yellow color, FIRST bring sections to ____ and wash with water
saturated solution of lithium carbonate in 70% alcohol
To remove picric acid yellow color, SECOND, place tissue in ___ followed by ____and then wash with running water
70% EtOH
5% Sodium thiosulfate
fixatives used at ice-cold temperature (-40C)
acetone
acetic acid fixative
fixative used only in enzyme studies
acetone
used for rapid denaturing and precipitation of proteins by destroying hydrogen bonds and other bonds
alcohol fixatives
alcohol fixatives must be used in conc. from what percent
70 to 100%
lesser conc of alcoholic fixatives will __ cells
LYSE
commonly known as osmic acid
osmium tetroxide fixative
color of osmium tetroxide fixative
pale yellow
strong OA
osmium tetroxide fixative
osmium tetroxide fixative dissolves in water up to about how many percent and at what temperature
6% at 20C
