Impregnation Flashcards
what is removed during the impregnation?
clearing agent
it will be replaced by a medium
ideal volume
at least 25x the volume of the tissue
enumerate the 3 methods of impregnation used in histology
- paraffin wax impregnation
- celloidin wax/collodion impregnation
- gelatin impregnation
simplest method and the best for routine use
what is melting point?
impregnation
paraffin wax impregnation
melting point: 54-58 C
most expensive impregnation method
gelatin impregnation
enumerate the 3 ways of paraffin wax impregnation and embedding
manual
automatic
vacuum embedding
this process requires at least 4 changes of wax with 15 mins interval
manual processing
total time: 1 hour
refers to the tissue processing machine which fixes, dehydrates, clears, and infiltrates tissues
autotechnicon
impregnation under negative atmospheric pressure which reduces 25-75% of impregnation time
vacuum embedding
vacuum embedding is recommended for __
urgent biopsies and delicate tissues
e.g., lung, brain, CT, decalcified bones, eyes, spleen, CNS
most rapid paraffin wax impregnation
vacuum embedding
temperature of paraffin:
temp of overheated paraffin:
temp of paraffin: 2-5C
overheated: above 60C
purified form of nitrocellulose soluble in many solvents
celloidin
celloidin is suitable for what specimens?
- specimens containing large cavities or hollow spaces which tend to collapse
- hard and dense tissues (bones and teeth)
- large tissue sections of whole embryos
enumerate the 2 methods for celloidin
- wet celloidin method
- dry celloidin method *Gilson’s mixture (equal parts of chloroform and cedarwood oil)
wet celloidin method is recommended for?
- bones
- teeth
- large brain sections
- whole organs
dry celloidin method is preferred for processing of?
whole eye sections
t or f: material embedded with the dry method can be cut without alcohol due to the presence of ___ in the block.
true.
presence of cedarwood oil
this method is rarely used except when dehydration is to be avoided and when tissues are to be subjected to histochemical and enzyme studies
gelatin impregnation
gelatin impregnation is used for?
delicate specimens and frozen tissue sections
bcos it prevents fragmentation
gelatin impregnation is water soluble, does not require ____ and __
dehydration and clearing
tissue thickness for gelatin impregnation should be _____ since gelatin embedded specimens are harder to freeze than non-impregnated tissues
not be more than 2-3 mm thick
this solution is used to prevent the growth of molds in pair with 20% gelatin
1% phenol
reagent to tissue ratio for fixation and decalcification
20:1
reagent to tissue ratio for dehydration and clearing
10:1
reagent to tissue ratio for infiltration
25:1
