INFILTRATION

Question 1

saturation of tissue cavities and cells by a supporting substance which is generally, but not always, the medium in which they are finally embedded.

Answer 1

Infiltration

Question 2

Tissues are infiltrated by immersion in a substance such as_____.

Alternatively, tissues can be infiltrated with a solution of a substance dissolved in a solvent, for example_____ in ______, which solidifies on evaporation of the solvent to provide a firm mass suitable for sectioning.

Answer 2

wax

nitrocellulose in alcohol-ether

Question 3

Ideally an infiltrating medium should be:

Answer 3

• soluble in processing fluids

• suitable for sectioning and ribboning

• molten between 30°C and 60°C

• translucent or transparent; colorless

• stable

• homogeneous

• capable of flattening after ribboning

• non-toxic

• odorless

• easy to handle

• inexpensive

Question 4

In addition the properties of the infiltrating medium should approach those of the tissues to be sectioned with regard to (5) and should be harmless to the embedded material.

Answer 4

density, elasticity, plasticity, viscosity and adhesion

Question 5

Infiltration may be done (3) method

Answer 5

manually
processed automatically
vacuum method

Question 6

The main advantage of manual processing over automated methods lies in the flexibility of_______, conditions and schedule design to provide optimum processing for small batches of tissues.

Answer 6

reagent selection

Question 7

The most common infiltration method is_____ infiltration.

Other methods include _____ and _____.

Answer 7

paraffin wax

celloidin infiltration and gelatin infiltration

Question 8

is a polycrystalline mixture of solid hydrocarbons produced during the refining of coal and mineral oils

Answer 8

Paraffin wax

Question 9

Wax hardness (viscosity) depends upon the _______of the components and the______

Answer 9

molecular weight

ambient temperature

Question 10

Paraffin wax

_________ melt at higher temperatures than waxes comprised of lower molecular weight fractions.

Answer 10

High molecular weight mixtures

Question 11

Paraffin wax

The wax is a solid at room temperature but melts at temperatures up to about_______

Answer 11

65°C or 70°C.

Question 12

Paraffin wax can be purchased with melting points at different temperatures, the most common for histological use being about______, At its melting point it tends to be slightly viscous, but this decreases as the temperature is increased.

Answer 12

56°C–58°C

Question 13

The traditional advice with paraffin wax is to use this about___ above its melting point.

Answer 13

2°C

Question 14

To decrease viscosity and improve infiltration of the tissue, technologists often increase the temperature to above_______ in practice to decrease viscosity.

Answer 14

60°C or 65°C

Question 15

improve ribboning:

Answer 15

prolong heating of paraffin wax at high temperatures or

use microcrystalline wax

Question 16

Modiefied paraffin wax

• increase hardness:

Answer 16

Add stearic acid

Question 17

Modified paraffin wax

decrease melting point:

Answer 17

add spermaceti or phenanthrene

Question 18

Modified paraffin wax

• improve adhesion between specimen and wax (alter crystalline morphology):

Answer 18

ADD either of the ff:

0.5% ceresin
0.1-5% beeswax
rubber
asphalt
bayberry wax
phenanthrene

Question 19

Early histological wax formulations have largely been replaced by uniform, high quality proprietary blends of histological paraffin waxes.

Additives recently incorporated in these waxes include the following:

Answer 19

1. Piccolyte 115
2. Plastic polymers
3. Dimethyl sulphoxide (DMSO)

Question 20

, a thermoplastic resin added at the rate of 5%-10% to the infiltrating wax, or to the final investing paraffin wax to improve tissue support for thin sectioning and facilitate flattening and expansion of sections on the waterbath.

Answer 20

Piccolyte 115

Question 21

% of Piccolyte 115 added to paraffin wax

Answer 21

5%-10%

Question 22

, added to improve adhesion, hardness and plasticity. Polymer waxes are incorporated in the majority of paraffin wax blends presently available.

Answer 22

Plastic polymers

Question 23

Plastic polymer example

Answer 23

polyethylene wax

Question 24

are incorporated in the majority of paraffin wax blends presently available.

Answer 24

Polymer waxes

Question 25

added to proprietary blends of plastic polymer paraffin waxes that reduces infiltration times and facilitates thin sectioning.

Answer 25

Dimethyl sulphoxide (DMSO)

Question 26

scavenges residual transition solvent and probably alters tissue permeability by substituting for or removing bound water thus improving infiltration.

Answer 26

Dimethyl sulphoxide (DMSO)

Question 27

Some individuals who handle _______may experience an unpleasant and annoying oyster or garlic taste probably caused by _____metabolites.

Answer 27

DMSO-paraffin wax

DMSO

Question 28

SUBSTITUTES FOR PARAFFIN WAX

Answer 28

Paraplast
Polyethylene glycols (PEG)
Carbowaxes
Ester waxes

Question 29

A modern paraffin embedding medium for tissue specimens is

Answer 29

Paraplast®

Question 30

highly purified paraffin with a melting point of 56ºC and formulated to give outstanding tissue infiltration and superior quality sections.

Answer 30

Paraplast®

Question 31

Melting point of highly purified paraffin with a melting point of Paraplast

Answer 31

56C

Question 32

Unlike some other tissue embedding products,______ is already doubly filtered, and there is no need for further filtration prior to use.

Answer 32

Paraplast

Question 33

are water soluble media used for investigation of heat and solvent-labile lipids and proteins

Answer 33

Polyethylene glycols (PEG)

Question 34

Used to overcome tissue shrinkage, damage and distortion inherent in the paraffin wax technique.

Answer 34

Polyethylene glycols (PEG)

Question 35

The polyethylene glycols, or_____, are polymers of varying length.

In general they are less elastic, denser and somewhat harder than paraffin wax.

Answer 35

Carbowaxes

Question 36

have low melting points, are hard at room temperature and have good adhesive properties.

Answer 36

Ester waxes

Question 37

They are ideal for supporting and serially sectioning refractory hard, criticized material such as arthropods, and tissues which heat-harden excessively

Answer 37

Ester wax

Question 38

used for simple investment of paraffin blocks to be sectioned under hot conditions and in double embedding with agar.

Answer 38

Ester wax

Question 39

are no longer commercially available and must be prepared from the basic ingredients.

Answer 39

Ester waxes

Question 40

Celloidin and Low Viscosity Nitrocellulose, mixtures of di- and tri-nitrocellulose, are composed of yellowish-white matted filaments with the appearance of_____.

Answer 40

raw cotton

Question 41

is insoluble in water, but soluble in absolute ethanoldiethyl ether, amyl acetate, methyl benzoate, methyl salicylate and 2ethoxyethanol and is set by most hydrocarbon solvents.

Answer 41

Nitrocellulose

Question 42

Nitrocellulose is insoluble in water, but soluble in (5)and is set by most hydrocarbon solvents.

Answer 42

absolute ethanoldiethyl ether
amyl acetate
methyl benzoate
methyl salicylate
2ethoxyethanol

Question 43

T or F

Nitrocellulose is highly flammable,

Answer 43

True

Question 44

Nitrocellulose must be kept_________ or as_________

Answer 44

alcohol-damped with n-butanol

8% solutions in ethanol-ether

Question 45

solutions have a low tolerance of water and dehydration must be thorough

Answer 45

Celloidin

Question 46

tolerates up to 6% of water, has superior penetration and final block hardness and is supplied in various grades of viscosity and nitrogen content.

Answer 46

low viscosity nitrocellulose (LVN)

Question 47

________tissue processing techniques are generally employed for sectioning hard tissues such as bone, for topographical studies of central nervous system tissues, or for delicate embryonic material.

Tissues are processed at room temperature producing minimal and shrinkage and hardening.

Answer 47

Nitrocellulose

Question 48

Infiltration sequence for specimens not more than 4mm thick.

Answer 48

1st paraffin wax bath - 30 mins
2nd paraffin wax bath - 30 mins
3rd paraffin wax bath - 45 mins

Question 49

Process whereby the clearing agent is completely removed from the tissue and replaced by a medium that will completely fill all the tissue cavities and give a firm consistency to the specimen.

Answer 49

Infiltration