Impregnation Flashcards
Other term for infiltration
Impregnation
process whereby the clearing agent is completely removed from the tissue giving a firm consistency
Infiltration/impregnation
allows easier handling and cutting of suitably thin sections without any damage or distortion to the tissue
Impregnation
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The volume of the infiltrating medium must not be less than
25 times
simplest, most common and best embedding medium used for routine tissue processing.
Paraffin wax
Common waxing melting points are
45, 52, 56 degree’s Celsius
These require wax with higher melting point than soft tissues.
Hard tissues
Not recommended because it has an increased time requirement.
Manual processing
At least 4 changes of wax are required at 15-minute intervals in order to ensure complete removal of the clearing agent
Manual processing
This uses an automatic tissue processing machine
Automated processing
Only 2-3 changes of wax are required to remove clearing agent properly
Automatic processing
to protect the wax against over-heating.
Safety device cut out switch
This os to protect the wax from overheating
Safety device cut out switch
moves the tissues from one processing reagent to another
Transfer arm
Involves wax impregnation under negative atmospheric pressure inside an embedding oven to hasten removal of air bubbles
Vacuum embedding
Most critical stage of tissue processing
Dehydration
This is the fastest results obtained
Vacuum embedding
helps speed up wax impregnation and removes any residual air bubbles.
Vacuum embedding
This technique is particularly recommended for urgent biopsies, for delicate tissues
Vacuum embedding
vacuum chamber is enclosed in a thermostatically controlled water-jacket, usually maintained at a temperature of
2-4 celsius above the melting point
The degree of the vacuum should not exceed
500 mmhg
Of the three methods of paraffin wax impregnation what gives the fastest result
Vacuum impregnation
Mixture of highly purified paraffin + synthetic plastic
polymers
Paraplast
More elastic and resilient than paraffin wax thereby permitting large, dense tissue blocks such as bones and brain to be cut easily with the same results as double embedding.
Paraplast
What is the melting point of paraplast
56-57C
the serial cutting of sections, end to end,
without disrupting the momentum.
Ribboning
synthetic wax substitute similar to
Paraplast; melting point: 56-58°C; less brittle and less compressible than Paraplast.
Embeddol
semisynthetic wax recommended for
embedding eyes
Bioloid
product of paraffin, containing
rubber, with the same property as Paraplast.
Tissue mat
It has a 46-48C melting point
Ester wax
Does not require dehydration and clearing of tissues
Water soluble waxes
Most commonly used polyethylene glycol containing 18 or more carbon atoms, solid at room temperature, soluble in and miscible with water
Carbowax
purified form of nitrocellulose soluble in many solvents
Celloidin
Suitable for large hollow cavities which tend to collapse, hard and dense tissues
Celloidin
Completely fills all tissue cavities which gives the tissue spx a firm consistency and allows easier handling and cutting of thin sections without further damage or
distortion to the tissue and its cellular components.
Celloidin impregnation
is recommended for bones, teeth, large brain sections and whole organs.
Wet celloidin method
preferred for processing of whole eye sections.
Dry celloidin method
Equal parts of chloroform and cedarwood oil
Gilson’s mixture
In the dry celloidin method this is not used for storage before cutting
70% alcohol
another celloidin soluble equal concentration of ether and alcohol but with a lower viscosity
Low viscosity nitrocellulose
Forms harder tissue block and makes cutting of thinner sections possible.
Low viscosity of nitrocellulose
added to prevent the tendency of tissues to crack when embedding chrome-mordanted tissues.
Plasticizers
If paraffin wax and celloidin is not available, this is the alternative.
Gelatin impregnation
When issues are to be subjected to histochemical and enzyme studies.
Gelatin impregnation
Aka casting or blocking
Embedding
Process by which an impregnated tissue is placed into a precisely arranged position in a mold
Embedding
Consists of 2-L shaped strips/heavy brass arranged on a flat metal plate
Leuckhart’s embedding mold
Blocks produced are even, with parallel sides and with a fairly shaped initial setting of wax
Leuckharts Embedding mold
Made up of series of interlocking plates resting on a flat metal base, forming several compartments
Compound embedding unit
Consists of special stainless steel base mold fitted with a plastic embedding ring
Plastic embedding rings and base molds
Block holder during cutting
Plastic embedding rings and base molds
Equipped with a warm plate and cold plate at -5C
Tissue tek system
White plastic cassette mold with detachable, perforated stainless steel hinge and snap-on lid
Tissue tek system
This is recommended for busy routine labs
Plastic ice trays
This is normally for embedding celloidin blocks, but also useful for paraffin wax blocks
Paper boats
Provides easy and accurate identification of specimen and avoids the confusion and interchange of tissue blocks
Paper boats
Rapid embedding of small and large volume of tissue specimen
Paper boats
This is recommended for hard tissues
Celloidin or Nitrocellulose method
This is obsolete due to the availability of resin containing paraffin waxes
Double embedding method
Tissues infiltrated with celloidin first and the embedded in paraffin wax
Double-embedding method
Recommended of small sections of celloidin block
Double-embedding method
Used to facilitate cutting of large blocks of dense firm tissues
Double embedding method
Superior results for light microscopic studies
Plastic (resin) embedding
Made up of esters pf acrylic or methacrylic acid
Acrylic plastic
Popular embedding medium for light microscopy and is also hydrophilic
Polygycol methacrylate
Ideal embedding medium for undecalcified bone
Methyl methacrylate
This is a catalyst acting as an active site for polymerization
Benzoyl peroxide
Agent that can speed up a chemical specimen
Catalyst
Active ingredient added to the plastic so that the plastic can decompose better to form phenyl radicals
Benzoyl peroxide
Can be produced spontaneously by heat or light
Radicals
Process of removing excess wax after embedding
Trimming
Coarse filter paper
Green’s No. 904
Melting point for water-soluble waxes
38-42C or 45-56C
