Impregnation

Question 1

what is removed during the impregnation?

Answer 1

clearing agent

it will be replaced by a medium

Question 2

ideal volume

Answer 2

at least 25x the volume of the tissue

Question 3

enumerate the 3 methods of impregnation used in histology

Answer 3

• paraffin wax impregnation
• celloidin wax/collodion impregnation
• gelatin impregnation

Question 4

simplest method and the best for routine use

what is melting point?

impregnation

Answer 4

paraffin wax impregnation

melting point: 54-58 C

Question 5

most expensive impregnation method

Answer 5

gelatin impregnation

Question 6

enumerate the 3 ways of paraffin wax impregnation and embedding

Answer 6

manual
automatic
vacuum embedding

Question 7

this process requires at least 4 changes of wax with 15 mins interval

Answer 7

manual processing

total time: 1 hour

Question 8

refers to the tissue processing machine which fixes, dehydrates, clears, and infiltrates tissues

Answer 8

autotechnicon

Question 9

impregnation under negative atmospheric pressure which reduces 25-75% of impregnation time

Answer 9

vacuum embedding

Question 10

vacuum embedding is recommended for __

Answer 10

urgent biopsies and delicate tissues

e.g., lung, brain, CT, decalcified bones, eyes, spleen, CNS

Question 11

most rapid paraffin wax impregnation

Answer 11

vacuum embedding

Question 12

temperature of paraffin:
temp of overheated paraffin:

Answer 12

temp of paraffin: 2-5C
overheated: above 60C

Question 13

purified form of nitrocellulose soluble in many solvents

Answer 13

celloidin

Question 14

celloidin is suitable for what specimens?

Answer 14

• specimens containing large cavities or hollow spaces which tend to collapse
• hard and dense tissues (bones and teeth)
• large tissue sections of whole embryos

Question 15

enumerate the 2 methods for celloidin

Answer 15

• wet celloidin method
• dry celloidin method *Gilson’s mixture (equal parts of chloroform and cedarwood oil)

Question 16

wet celloidin method is recommended for?

Answer 16

• bones
• teeth
• large brain sections
• whole organs

Question 17

dry celloidin method is preferred for processing of?

Answer 17

whole eye sections

Question 18

t or f: material embedded with the dry method can be cut without alcohol due to the presence of ___ in the block.

Answer 18

true.

presence of cedarwood oil

Question 19

this method is rarely used except when dehydration is to be avoided and when tissues are to be subjected to histochemical and enzyme studies

Answer 19

gelatin impregnation

Question 20

gelatin impregnation is used for?

Answer 20

delicate specimens and frozen tissue sections

bcos it prevents fragmentation

Question 21

gelatin impregnation is water soluble, does not require ____ and __

Answer 21

dehydration and clearing

Question 22

tissue thickness for gelatin impregnation should be _____ since gelatin embedded specimens are harder to freeze than non-impregnated tissues

Answer 22

not be more than 2-3 mm thick

Question 23

this solution is used to prevent the growth of molds in pair with 20% gelatin

Answer 23

1% phenol

Question 24

reagent to tissue ratio for fixation and decalcification

Answer 24

20:1

Question 25

reagent to tissue ratio for dehydration and clearing

Answer 25

10:1

Question 26

reagent to tissue ratio for infiltration

Answer 26

25:1