Infiltration & Embedding

Question 1

mechanisms of solidification:

1. crystallization
2. evaporation of solvent
3. polymerization

Answer 1

1. paraffin & carbowax
2. celloidin
3. plastic

Question 2

CONSIDERATIONS IN PARAFFIN PROCESSING:

Lab temp
1. room temperature
2. cold temperature

Temperature During Infiltration
1. paraffin oven: ___ higher than MP of the wax
2. beyond ___: deleterious to tissue; complete damage of lymphoid

Number of Changes
1. at least:

Clearing Agent Used
1. easy removal
2. difficult

Answer 2

Lab temp
1. 54–58C (56C)
2. 50-54C

Temperature During Infiltration
1. 2–5C
2. beyond 60C

Number of Changes
1. 2 changes

Clearing Agent Used
1. xylene/benzene
2. chloroform/cedarwood oil

Question 3

Methods of Paraffin Impregnation

Manual Processing
1. ___ changes at 15min interval
2. ___higher than MP of wax

Automatic Processing
1. ___ changes w/ agitation
2. at least ___ higher than the MP of the wax

Vacuum Embedding
1. ____ changes
2. ____ higher than the MP of the wax
3. negative atmospheric pressure (_____ mmHg)

Answer 3

Manual Processing
1. 4 changes
2. 2-5C

Automatic Processing
1. 2-3 changes
2. 3C

Vacuum Embedding
1. 3 changes
2. 2-4C
3. 400-500 mmHg

Question 4

Paraffin Embedding
1. melted paraffin: ____ above the MP of wax
2. cooling:
- ref at ____
- immerse in _____
- _____ w/ cold plate

Answer 4

1. 5-10
   2.
   - -5
   - cold water
   - tissue tek

Question 5

Substitutes for Paraffin Wax

1. more elastic & resilient (doesn’t crumble)
   - MP
2. soluble in 95% EA & other clearing agents
   - MP
3. polyethylene glycols
   - MP

Answer 5

1. Paraplast
   - 56-57C
2. Ester Wax
   - 46-48
3. Water Soluble Waxes
   - 38-42C or 45-56C

Question 6

Paraplast
1. less brittle than paraplast ( MP)
2. semisynthetic wax that is used in impregnating and
embedding eye samples
3. product of paraffin that contains rubber

Answer 6

1. Embeddol
2. Bioloid
3. Tissue Mat

Question 7

Carbowax
1. disadvantage: ____ reagent (highly soluble in water)
2. remedy:
- add __ or ____ on waterbath
- use floating sol’n: ____ (formalin, diethyl glycol,
dist. water)/ ____ (gelatin, K2CrO4)

Answer 7

1. hygroscopic
2. remedy:
   - soap or 10% polyethylene glycol 900
   - Pearse sol’n; Blank & McCarthy sol’n

Question 8

CELLOIDIN/ COLLODION
1. Aka
2. available in thin (%), medium (%) & thick (_%) solutions
3. Other celloidin
- soluble in equal concentrations of ether & alcohol
- curled strips of cellulose

Answer 8

1. Purified Pyroxylin Nitrocellulose
2. Thin (2%), medium (4%) & thick (8%)
   3.
   - Low Viscosity
   Nitrocellulose
   - Parlodion

Question 9

Methods of Celloidin
1. for bones, teeth large brain sections & whole organs
- thin celloidin
- medium
- thick
- storage
2. for whole eye section
- (chloroform + cedarwood oil) is added to fresh thick
celloidin during embedding

Answer 9

1. Wet Method
   - 2-4 % (5-7 days)
   - 4-6 % (5-7 days)
   - 8- 12 % (3-5 days)
   - 70-80% alcohol
2. Dry Method
   - Gilson’s Mixture

Question 10

Types of Plastic Media

Epoxy
1. slowest
2. mid
3. fastest
**
1. for electron microscopy
**
1. for high resolution light microscopy
- valued for its hydrophilic nature
- valued for its hardness
- added as catalyst (for drying)

Answer 10

Epoxy
1. Araldite base (bisphenol)
2. Glycerol base (epon)
3. Cyclohexene Dioxide (spurr)
**
1. Polyester
**
1. Acrylic
- Glycol Methacrylate
- Methyl Methacrylate
- Benzoyl Peroxide

Question 11

______: for histochemical & enzyme studies; delicate specimens; frozen sections

1. ____ & ___ are not needed
2. tissue size
3. volume
4. all gelatin reagents contain ____

Answer 11

GELATIN

1. dehydration & clearing
2. 2-3mm thick
3. 25x
4. 1% phenol