CLEARING/IMPREGNATION/EMBEDDING Flashcards
Removal of dehydrating agent from the tissues and replacing it by a solvent
Clearing
Removal of dehydrating agent from the tissues and replacing it by a solvent
Clearing
Produce transparent and translucent tissue
Clearing
True or false
- not all dealcoholizing agents act as clearing agent
True
When is clearing in embedding done
Done after dehydration and before infiltration
Agents for clearing in embedding
- xylene
- toluene
- Dioxane
- chloroform
When is clearing in mounting done
Done after staining and before mounting
Agents of mounting media
- xylene
- toluene
- terpineol
- carbol - xylene
An ideal clearing agent should be miscible with
Alcohol and paraffin wax
Most commonly and rapidly used clearing agent
Xylene/ xylol
Duration of xylene
15-30 mins or 30 mins - 1 hr
Excellent clearing agent but tends to make tissues excessively hard and brittle
Xylene/xylol
Can be used for celloidin sections
Xylene
Unsuitable for brain and lymph nodes
Xylene
Turns milky when dehydration is not complete
Xylene
Rapid agent and highly inflammable; doesn’t make tissues hard and brittle but may cause considerable shrinkage
Benzene
Excessive exposure to this may be extremely toxic to man and may become carcinogenic or it may damage the bone marrow resulting in aplastic anemia
Benzene
Duration of benzene
15-60 mins
Similar to xylene but does not harden tissues nearly so much
Toluene/toloul
Slower than xylene or benzene, it is not carcinogenic but emits toxic fumes
Toluene
Duration of toulene or toluol
1-2 hours
For nervous tissues, lymph nodes, and embryos
Chloroform
Best for large specimens and tough tissues
Chloroform
Little shrinkage and doss not harden tissues excessively; not flammable
Chloroform
Slow and doesn’t make tissues transparent, it is toxic to the liver on prolonged inhalation
Chloroform
Tissues tend to float in chloroform, how to avoid this
Wrap the tissues with absorbent cotton gauze to facilitate sinking of the section in solution
Recommended for CNS, smooth muscles, and skin
Cedarwood oil
Used to clear both paraffin and celloidin sections during the embedding process
Cedarwood oil
Duration of clearing using Cedarwood oil
2-3 days
Slow clearing (2-3 days) with minimal shrinkage
Cedarwood oil
Must be followed by immersion in xylene or benzene to remove oil from tissues, and must be filtered prior to using
Cedarwood oil
Turns milky on prolonged storage
Cedarwood oil
Tissue floats in cedarwood oil, what is the remedy
Superimpose with absolute alcohol
This is not normally utilized as a routine agent but it is recommended for clearing embryos, insects, and very delicate specimens, due to its ability to clear 70% alcohol without excessive tissue shrinkage and hardening
Aniline oil
It has the ability to clear 70% alcohol without excessive tissue shrinkage and hardening
Aniline oil
Slow, may be adultered, removes aniline dyes
Clove oil
Aniline dyes are removed, and celloidin is dissolved
Clove oil
Similar to chloroform
CCL4
Fill all natural cavities, spaces and interstices of the tissue with a firm consistency
Impregnation or infiltration
Impregnated tissues are placed into a precisely arranged position in a mold containing a medium which is the allowed to solidify
Embedding, blocking, or casting
Simplest, most common and best embedding medium used for routine tissue processing
Paraffin wax
Shrinks about 10% on cooling
Paraffin wax
Melting point for normal routine work
56C
At what temp should the paraffin oven adjusted
2-5C higher
Temperature adjustment if the lab temp is 20-24C
54-58C
Temperature adjustment if lab temp is 15-18C
50-54C