Infiltration and embedding Flashcards
Process whereby the clearing agent is completely removed from the tissue & replaced by a medium that
will completely fill all the tissue cavities, thereby giving a firm consistency to the specimen
impregnation
the process by which the impregnated
tissue is placed into a precisely arranged position in a mold containing a
medium which is then allowed to solidify
embedding
the simplest, most common and best embedding
medium used for routine tissue processing.
paraffin
Paraffin is solid at room temperature but melts at temperatures up to about
65-70C
not recommended for fatty
tissues.
paraffin wax
Three ways by which Paraffin wax impregnation and
embedding may be performed
- manual processing
- automatic processing
- vacuum embedding
The machine is mounted on
rollers to permit the turning of
platforms and easy access to
beakers and wax baths
Elliott bench type processor
The clearing agent and the dilute ethanols should be changed
at least once a week.
Wax bath thermostats should be set at least
3 degrees above the melting
point of the wax
involves wax impregnation under negative
atmospheric pressure inside an embedding oven.
Vacuum embedding
recommended for urgent biopsies
vacuum embedding
Substitutes for Paraffin Wax
Paraplast
Ester wax
Water soluble waxes
Not soluble in water but soluble in 95%EA, can be
used for impregnation without prior clearing of
tissue
Ester wax
does not require dehydration and clearing
carbowax
- suitable for many enzyme histochemical studies
carbowax
suitable for specimens with large hollow cavities which tend to collapse
celloidin
It does not require heat during processing
celloidin
recommended for bones, teeth, large brain sections and whole organs
Wet Celloidin Method
preferred for processing of whole eye sections
Dry Celloidin Method
Gilson’s mixture
equal part of chloroform and cedarwood oil
example of plasticizer
oleum ricini or castor oil
rarely used except when dehydration is to be avoided and when tissues are to be subjected to histochemical and
enzyme studies
Gelatin impregnation
After impregnation, the tissue is placed into a mold
containing the embedding medium and this medium is
allowed to solidify.
embedding
the process by which a tissue is arranged in precise positions in the mold during embedding, on the
microtome before cutting, and on the slide before
staining
orientation
used to be recommended for embedding hard tissues
such as bones and teeth, and for large sections of whole organs
Celloidin or Nitrocellulose Embedding Method
used to control the rate of the evaporation of the solvent
bell jars
recommended for making small sections of celloidin blocks.
double embedding
