CLEARING & IMPREGNATION Flashcards
the process whereby ALCOHOL OR A DEHYDRATING AGENT IS REMOVED FROM THE TISSUE and replaced by a fluid that will dissolve the wax with which the tissue must be impregnated
CLEARING
Clearing is also known as…
DEALCOHOLIZATION
the word CLEARING is used because in addition to removing alcohol, many of these substances have the property of making tissues __________ and ____________
TRANSPARENT (or TRANSLUCENT), CLEAR
the Refractive Index (RI) of clearing agents is approximately ________ to that of the tissues
EQUAL (OR CLOSE)
IDEAL amount of clearing agent
10x
NOT LESS THAN 10x the vol of the tse
what 2 agents are used when the tissue is cleared DIRECTLY FROM WATER (frozen section)
GUM SYRUP & GLYCERIN
an EXCELLENT and TRUE CLEARING AGENT
XYLENE
the MOST RAPID CLEARING AGENT
XYLENE
clearing agent that can also be used with celloidin sections
XYLENE
when dehydration is not complete, xylene becomes _________ when the tissue or section is added to it
MILKY
clearing agent NOT RECOMMENDED for NERVOUS TISSUES and LYMPH NODES
XYLENE
SUBSTITUTE for xylene or benzene
TOLUENE
USUAL clearing time of Xylene
30 mins - 2 hours
Xylene clearing time for URGENT BIOPSIES
15-30 minutes
it is NOT CARCINOGENIC but highly concentrated emit fumes that are toxic upon prolonged exposure
TOLUENE
acts SLOWER THAN BENZENE and is EXPENSIVE
TOLUENE
rapid acting, RECOMMENDED FOR URGENT BIOPSIES and routine purposes
BENZENE
URGENT - BENZENE
clearing agent that is HIGHLY FLAMMABLE
BENZENE
clearing agent: CARCINOGENIC or may DAMAGE BONE MARROW
BENZENE
clearing agent that may cause APLASTIC ANEMIA
BENZENE
it is the BEST OF THE TRADITIONAL clearing agents for routine use
CHLOROFORM
clearing agent that gives the WIDEST LATITUDE
CHLOROFORM
recommended for TOUGH SKIN AND LARGE TISSUE SPECIMENS
CHLOROFORM 👺
BEST for NERVOUS TISSUE, LYMPH NODES, GRANULATION TISSUE, and FETAL AND OTHER DELICATE, HIGHLY CELLULAR SPX
CHLOROFORM
it does NOT MAKE tissues TRANSPARENT
CHLOROFORM
clearing agent toxic to the liver (HEPATOTOXIC) after prolonged inhalation
CHLOROFORM
clears BOTH PARAFFIN and CELLOIDIN SECTIONS
CEDARWOOD OIL
RECOMMENDED for CNS TISSUES and CYTOLOGICAL studies
CEDARWOOD OIL
CCC: CEDARWOOD, CNS, CYTOLOGICAL!!!
how many changes does Cedarwood Oil need in clearing solution?
2 CHANGES
clearing agent:
quality is NOT ALWAYS UNIFORM AND GOOD and is extremely slow
CEDARWOOD OIL
becomes MILKY ON PROLONGED STORAGE
CEDARWOOD OIL
RECOMMENDED for clearing EMBRYOS, INSECTS, and VERY DELICATE SPX
ANILINE OIL
clue: VERY DELICATE 🧚♀️
clearing agent:
removes aniline dyes and dissolves celloidin
CLOVE OIL
clearing agent:
its quality is NOT GUARANTEED due to its tendency to be ADULTERED
CLOVE OIL
properties are VERY SIMILAR TO CHLOROFORM but it is cheaper; toxic on prolonged exposure
CARBONTETRACHLORIDE
(CCl4)
DEHYDRATES and CLEARS at the same time since it is miscible in both water and paraffin
TETRAHYDROFURAN
2 clearing agents: slow-acting clearing agents that can be used when DOUBLE-EMBEDDING TECHNIQUES are required
- METHYL BENZOATE
- METHYL SALICYLATE
the process whereby the CLEARING AGENT IS COMPLETELY REMOVED FROM THE TISSUE and replaced by a medium
IMPREGNATION
another term for Impregnation
INFILTRATION
IDEAL VOLUME of impregnating agent
25x
NOT LESS THAN 25X the vol of the tse
3 methods of IMPREGNATION used in Histology
- PARAFFIN WAX
- CELLOIDIN WAX
- GELATIN
METHODS OF IMPREGNATION:
the SIMPLEST, MOST COMMON, and by far THE BEST FOR ROUTINE USE
PARAFFIN WAX IMPREGNATION
MELTING POINT OF PARAFFIN WAX
54-58°C
3 WAYS OF PARAFFIN WAX IMPREGNATION (and EMBEDDING)
- MANUAL PROCESSING
- AUTOMATIC PROCESSING
- VACUUM EMBEDDING
WAYS OF PARAFFIN WAX IMPREGNATION
method that requires AT LEAST 4 CHANGES OF WAX with 15 MINUTES INTERVAL
MANUAL PROCESSING
WAYS OF PARAFFIN WAX IMPREGNATION
How many changes of wax does the manual processing require?
4 changes
WAYS OF PARAFFIN WAX IMPREGNATION
makes use of an automatic tissue processing machine, thereby decreasing the time and labor
AUTOMATIC PROCESSING
WAYS OF PARAFFIN WAX IMPREGNATION
example of machine used in Automatic Processing
AUTOTECHNICON
WAYS OF PARAFFIN WAX IMPREGNATION
AUTOMATIC PROCESSING involves what steps?
- FIXATION
- DEHYDRATION
- CLEARING
- INFILTRATION
WAYS OF PARAFFIN WAX IMPREGNATION
impregnation under NEGATIVE ATMOSPHERIC PRESSURE
VACUUM EMBEDDING
WAYS OF PARAFFIN WAX IMPREGNATION
a vacuum of up to ________ mmHg is applied using a water or mechanical pump
760 mmHg
WAYS OF PARAFFIN WAX IMPREGNATION
MOST RAPID wax impregnation; gives the FASTEST RESULT
VACUUM EMBEDDING
WAYS OF PARAFFIN WAX IMPREGNATION
RECOMMENDED for URGENT BIOPSIES & DELICATE TISSUES such as lung, brain, connective tses, decalcified bones, eyes, spleen, and CNS
VACUUM EMBEDDING
WAYS OF PARAFFIN WAX IMPREGNATION
Vacuum Embedding reduces how many percent of impregnation time?
25-75%
3 SUBSTITUTES for Paraffin Wax
- PARAPLAST
- ESTER WAX
- WATER SOLUBLE WAXES
SUBSTITUTES FOR PARAFFIN WAX
a mixture of highly purified PARAFFIN WAX and SYNTHETIC PLASTIC POLYMERS
PARAPLAST
MELTING POINT of Paraplast
56-57°C
a synthetic wax substitute to Paraplast; less brittle and less compressible than Paraplast
EMBEDDOL
MELTING POINT of Embeddol
56-58°C
a semisynthetic wax RECOMMENDED FOR EMBEDDING EYES
BIOLOID
MELTING POINT of Ester Wax
46-48°C
wax harder than paraffin; not soluble in water but SOLUBLE IN 95% ETHYL ALCOHOL and other clearing agents
ESTER WAX
“ETHYL-ESTER”
these are mostly polyethylene glycols with melting points of 38-42°C or 45-56°C
WATER SOLUBLE WAXES
MOST COMMONLY USED POLYETHYLENE GLYCOL
CARBOWAX
at what temperature does Carbowax appear SOLID?
ROOM TEMPERATURE
wax SOLUBLE IN WATER, hence DOES NOT REQUIRE DEHYDRATION AND CLEARING of the tse
CARBOWAX
wax suitable for many ENZYME HISTOCHEMICAL STUDIES
CARBOWAX
PARAFFIN OVEN must be maintained at what temperature?
2-5°C ABOVE the MELTING POINT OF THE WAX
When wax has been reused, some amount of water is inevitably mixed with it. To remove water, WAX MUST BE HEATED to what temperature?
100-105°C
How many times is Paraffin Wax allowed to be used?
TWICE (2x)
to remove grit & dirt BEFORE EMBEDDING, what must be done to the paraffin wax?
FILTERED
purified form of NITROCELLULOSE soluble in many solvents
CELLOIDIN
suitable for specimens containing LARGE CAVITIES or HOLLOW SPACES which tend to collapse; also for WHOLE EMBRYOS and WHOLE ORGANS LIKE EYES
CELLOIDIN IMPREGNATION
2 METHODS FOR CELLOIDIN
- WET CELLOIDIN METHOD
- DRY CELLOIDIN METHOD
METHOD FOR CELLOIDIN
RECOMMENDED for BONES, TEETH, LARGE BRAIN SECTIONS, and WHOLE ORGANS
WET CELLOIDIN METHOD
METHOD FOR CELLOIDIN
in Wet Celloidin Method, tissues must be CUT WET where both the knife and tissue block are kept moist with what reagent while cutting?
70% ALCOHOL
METHOD FOR CELLOIDIN
PREFERRED for processing of WHOLE EYE SECTIONS
DRY CELLOIDIN METHOD
DRY - EYE
material embedded with the dry method can be cut WITHOUT ALCOHOL due to the presence of what reagent in the block?
CEDARWOOD OIL
GILSON’S MIXTURE COMPOSITION
EQUAL PARTS OF CHLOROFORM & CEDARWOOD OIL (1:1)
another form of celloidin soluble in EQUAL CONCENTRATION of ETHER and ALCOHOL
LOW VISCOSITY NITROCELLULOSE
Low Viscosity Nitrocellulose (LVN) is made of equal concentration of what 2 reagents?
ETHER and ALCOHOL
method of impregnation used when DEHYDRATION IS TO BE AVOIDED
GELATIN IMPREGNATION
impregnation method used when tissues are to be subjected to HISTOCHEMICAL AND ENZYME STUDIES
GELATIN IMPREGNATION
impregnation method that DOES NOT REQUIRE DEHYDRATION AND CLEARING
GELATIN IMPREGNATION
