GPHT LAB - Fixation Handouts

Question 1

grp of fixatives satisfactory for routine paraffin sections, frozen sections, and for EM

Answer 1

aldehyde fixatives

Question 2

gas produced by oxidation of MetOH

Answer 2

formaldehyde

Question 3

HCHO soluble in water to the extent of ___ by weight

Answer 3

40%

Question 4

powerful RA, used in the make up of Helly’s fluid

Answer 4

formaldehyde

Question 5

purest solution (how many percent) of formaldehyde

Answer 5

40%

Question 6

routine formalin sol’n how many percent

Answer 6

10%

Question 7

how to prep routine formalin sol’n

Answer 7

10 ml strong HCHO

90 ml H20 or saline

Question 8

dilution of routine formalin sol’n

Answer 8

1:10

Question 9

usual fixation time of HCHO

Answer 9

12-24 hrs

Question 10

often becomes turbid

Answer 10

commercial HCHO

Question 11

why does commercial HCHO become turbid after prolonged storage

Answer 11

due to formation of paraformaldehyde which is caused by HCHO polarization

Question 12

presence does not impair fixing qualities of HCHO

Answer 12

paraformaldehyde

Question 13

removal of formalin pigments methods (3)

Answer 13

Kardasewitsch’s
Lillie’s
Picric Acid Method

Question 14

what method of removal of formalin pigments

section placed for 5 min - 2 hrs in 70% EtOH, 28% NH3 water

Answer 14

Kardasewitsch’s

Question 15

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

Answer 15

Lillie’s

Question 16

section placed for 5 min - 2 hrs in std solution of picric acid
washed in running water for 11-15 min

Answer 16

picric acid method

Question 17

aldehyde MW 100 or 2 formaldehyde residues linked by a striaght 3C chains

Answer 17

glutaraldehyde

Question 18

best used for small fragments and small needle biopsies

Answer 18

2.5% glutaraldehyde

Question 19

for larger tissue not exceeding 4mm in thickness, for 12-24 hrs at RT

Answer 19

4% solution of glutaraldehyde

Question 20

polymer of formaldehyde, white powder

Answer 20

paraformaldehyde

Question 21

used in a 4% strength at 4c

Answer 21

paraformaldehyde

Question 22

frequently used in saturated soln

Answer 22

mercuric chloride

Question 23

solubility of HgCl2 in water at RT

Answer 23

7%

Question 24

in removing mercuric chloride granules, sections are placed in alcoholic iodine for 1-2 min. give exact composition of alcoholic iodine

Answer 24

0.5 ml iodine in 100 ml 70% EtOH

Question 25

in removing mercuric chloride granules, sections are rinsed in water and placed in _____ for 1-2 min to remove iodine

Answer 25

5% sodium thiosulfate (hypo) solution

Question 26

used in 1-2% aqueous solution

Answer 26

chromate fixatives

Question 27

strong OA, should not combine with RA like alcohol and formalin

Answer 27

chromate fixatives

Question 28

used in 3% aq. sol’n

Answer 28

potassium dichromate

Question 29

strong fixative for certain lipids

Answer 29

potassium dichromate

Question 30

used in 4% aq solution

Answer 30

lead fixatives

Question 31

used in strong or sat. solution

Answer 31

picric acid fixative

Question 32

picric acid chemical name

Answer 32

2,4,6-trinitrophenol

Question 33

how many grams Picric acid will dissolve in 100 ml of dist. H20 and at what temperature

Answer 33

1.7 g

15C

Question 34

To remove picric acid yellow color, FIRST bring sections to ____ and wash with water

Answer 34

saturated solution of lithium carbonate in 70% alcohol

Question 35

To remove picric acid yellow color, SECOND, place tissue in ___ followed by ____and then wash with running water

Answer 35

70% EtOH

5% Sodium thiosulfate

Question 36

fixatives used at ice-cold temperature (-40C)

Answer 36

acetone

acetic acid fixative

Question 37

fixative used only in enzyme studies

Answer 37

acetone

Question 38

used for rapid denaturing and precipitation of proteins by destroying hydrogen bonds and other bonds

Answer 38

alcohol fixatives

Question 39

alcohol fixatives must be used in conc. from what percent

Answer 39

70 to 100%

Question 40

lesser conc of alcoholic fixatives will __ cells

Answer 40

LYSE

Question 41

commonly known as osmic acid

Answer 41

osmium tetroxide fixative

Question 42

color of osmium tetroxide fixative

Answer 42

pale yellow

Question 43

strong OA

Answer 43

osmium tetroxide fixative

Question 44

osmium tetroxide fixative dissolves in water up to about how many percent and at what temperature

Answer 44

6% at 20C