IMPREGNATION AND EMBEDDING Flashcards
___has a wide range of melting points which is important for use in the fifferent climactic regions of the world
Inexpensive
Provides quality sections
Can be used for most routine and special stains
Paraffin wax
LOW MELTING POINT PARAFFIN – usually softer
HIGH MELTING POINT PARAFFIN – usually harder
Melting points range from ___ (commonly 56C)
40-70C
Paraffin wax that contains plasticizers or other resin additives are commercially available
These mixtures create paraffin with the desired hardness for the tissues to be embedded
Additives have a high melting point than paraffin which makes the tissues brittle.
Examples:
Beeswax Rubber Ceresin Plastic polymers Diethylene glycol disteareate
Sub for paraffin wax.
Is a mixture of highly purified paraffin and synthetic plastic polymers
Melting point: 56-57C
More elastic and resilient than paraffin wax thereby permitting large dense tissue blocks such as bones and brain to be easilt cut
Better ribboning of tissues and serial sectioning is allowed
PARAPLAST
similar to paraplast with a melting point of 56-58C which is less pressible than paraplast
EMBEDDOL
recommended for embedding eyes
BIOLOID
paraffin plus rubber with the same property as paraplast
TISSUE MAT –
Lower melting point (46-48C) but is harder than paraffin
Non water soluble but is soluble in 95% ethyl alcohol and other clearing agents
Three to four changes are needed
Cutting should be done with a sliding or sledge type microtome
ESTER WAX
Mostly are polyethylene glycols with melting points of 38-42C or 45-56C
WATER SOLUBLE WAXES
appears solid at room temperature
Does not need dehydration and clearing
Does not remove neutral wax
Good for enzymatic studies
Used in four changes : 70% (30mins)-90% (45 mins) and 100% (X2) (1H) at a temperature of 56C
Tissues are difficult to float out due to water miscibility (remedied by _ or _ )
CARBOWAX
soap or 10% polyethylene glycol 900
Also known as COLLODION
Is a purified form of nitrocellulose soluble in many solvents suitable for specimens with large hollow cavities which tend to collapse, for hard and dense tissues such as bones and teeth and large tissue sections of the embryo
Supplied in:
CELLOIDIN
Thin (2%)
Medium (4%)
Thick (8%)
Disadv.
Impregnation is very slow (days to week) Very thin sections (less than 10u) are difficult to cut Serial sections are different to prepare Vapor of ether solvent is very flammable Photomicrographs are difficult to obtain Very volatile
CELLOIDIN
Cellodin Methods
Recommended for bones, teeth, large brain sections, and whole organs
Recommended for the eyes
WET METHOD
DRY METHOD
involves the enclosing of properly processed, correctly oriented specimens in a support medium that provides external support during microtomy
EMBEDDING
consists of two L shaped strips of heavy brass or metal arranged on a flat metal plate
LEUCKHART’S EMBEDDING MOLD
is made up of a series of interlocking plates resting on a flat metal base forming several compartments
COMPOUND EMBEDDING UNIT
DISPOSABLE EMBEDDING MOLDS
3
Peel away
Plastic ice trays
Paper boats