GPHT LAB - Fixation Handouts Flashcards Preview

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Flashcards in GPHT LAB - Fixation Handouts Deck (44)
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1

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

aldehyde fixatives

2

gas produced by oxidation of MetOH

formaldehyde

3

HCHO soluble in water to the extent of ___ by weight

40%

4

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

formaldehyde

5

purest solution (how many percent) of formaldehyde

40%

6

routine formalin sol'n how many percent

10%

7

how to prep routine formalin sol'n

10 ml strong HCHO
90 ml H20 or saline

8

dilution of routine formalin sol'n

1:10

9

usual fixation time of HCHO

12-24 hrs

10

often becomes turbid

commercial HCHO

11

why does commercial HCHO become turbid after prolonged storage

due to formation of paraformaldehyde which is caused by HCHO polarization

12

presence does not impair fixing qualities of HCHO

paraformaldehyde

13

removal of formalin pigments methods (3)

Kardasewitsch's
Lillie's
Picric Acid Method

14

what method of removal of formalin pigments
section placed for 5 min - 2 hrs in 70% EtOH, 28% NH3 water

Kardasewitsch's

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

Lillie's

16

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

picric acid method

17

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

glutaraldehyde

18

best used for small fragments and small needle biopsies

2.5% glutaraldehyde

19

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

4% solution of glutaraldehyde

20

polymer of formaldehyde, white powder

paraformaldehyde

21

used in a 4% strength at 4c

paraformaldehyde

22

frequently used in saturated soln

mercuric chloride

23

solubility of HgCl2 in water at RT

7%

24

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

25

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

26

used in 1-2% aqueous solution

chromate fixatives

27

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

chromate fixatives

28

used in 3% aq. sol'n

potassium dichromate

29

strong fixative for certain lipids

potassium dichromate

30

used in 4% aq solution

lead fixatives

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