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Histopathology > Impregnation and Embedding > Flashcards

Impregnation and Embedding Flashcards

1
Q

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

A

Impregnation (infiltration)

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2
Q

Enumerate 4 types of embedding and impregnation media.

A
  1. Paraffin Wax
  2. Celloidin
  3. Gelatin
  4. Plastic
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3
Q

What is the most common, simplest, and best embedding medium used for routine tissue processing?

A

Paraffin wax

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4
Q

What medium allows cut sections to stick together edge-to-edge, forming a “ribbon” of sections, but is not recommended for fatty tissues?

A

Paraffin wax

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5
Q

True or False.

An overheated specimen makes the specimen to be brittle.

A

True

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6
Q

What is the melting point of paraffin wax?

A

56°C - 58°C

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7
Q

What is the melting point of a paraplast?

A

56°-57°C

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8
Q

What is the melting point of a embeddol?

A

56°-58°C

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9
Q

Identify the type of paraffin wax.

  • More elastic/resilient
  • Permits large dense tissue blocks (bones & brain) to be cut easily
  • Better ribboning of sections
A

Paraplast

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10
Q

Identify the type of paraffin wax.

  • Synthetic wax substitute similar to Paraplast
  • Less brittle and compressible than Paraplast.
A

Embeddol

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11
Q

Identify the type of paraffin wax.

  • Harder than paraffin wax
  • H2O insoluble
  • Can be used for impregnation without prior clearing of tissue.
A

Ester wax

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12
Q

What is the melting point of ester wax?

A

46°-48°C

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13
Q

What is the other name for water-soluble waxes?

A

polyethylene glycol

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14
Q

What is the melting point of polyethylene glycol?

A

38°-42°C

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15
Q

What refers to the primary processor that is used today whereby tissue is stationary and fluids are pumped in and out of the pressurized chamber holding the tissue?

A

Closed system

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16
Q

What is the major advantage of using a closed system for tissue processors?

A

specimens cannot dry out in the tissue chamber in the event of malfunction

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17
Q

What is added to plastic polymer paraffin waxes that reduces infiltration time?

A

Dimethyl sulphoxide (DMSO)

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18
Q

A purified form of nitrocellulose soluble in many solvents

A

Celloidin

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19
Q

Identify the media.

  • Permits cutting of thicker tissue sections
  • Crumbling of tissues avoided (flexible to use)
  • Suitable for specimens with large cavities
  • For hard and dense tissues
  • For large tissue sections of the whole embryo
  • Also recommended for processing of neurological tissues
A

Celloidin

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20
Q

Identify the media.

  • Rarely used except when dehydration is to be avoided and when tissues are subjected to histochemical and enzyme studies
  • Used as an embedding medium for delicate specimens and frozen section specimen
  • Does not require dehydration & clearing
A

Gelatin

21
Q

Identify the media.

  • For Tiny tissues
  • Electron microscopy
  • Used for automation
A

Plastic

22
Q

Identify the method of celloidin impregnation.

  • for bones, teeth, large brain sections, and whole organ
A

Wet celloidin method

23
Q

Identify the method of celloidin impregnation.

  • for processing the whole eye section
A

Dry celloidin method

24
Q

What paraffin wax method is the fastest and has negative atmospheric pressure that facilitates the complete removal of transition solvents?

A

Vacuum

25
Q

How many changes of wax are done on the manual paraffin wax method?

A

4 changes

26
Q

What is the time interval between changes of wax during the manual paraffin wax method?

A

15 mins. interval

27
Q

True or False.

Tissues during gelatin impregnation should not be > 2-3 mm thick since gelatin-embedded specimens are harder to freeze than non-impregnated tissues.

A

True

28
Q
  • Also known as Blocking or Casting.
  • Process by which the impregnated tissue is placed into a precisely arranged positioning of a mold containing a medium which is then allowed to solidify.
A

Embedding

29
Q

What refers to the formation of tissue block?

A

blocking

30
Q

What refers to the process of placing the tissue in a molder?

A

Molding

31
Q

It is the process by which tissue is arranged in a precise position in the mold during embedding, on the microtome, before cutting, and on the slide before staining.

A

Orientation

32
Q

What temperature are paraffin-embedded tissues are cooled?

A

-5℃

33
Q

Identify the type of embedding.

  • 2% Celloidin for 3 days and subsequent paraffin
  • For large blocks of dense firm tissues (brain)
  • Obsolete
A

Double embedding

34
Q

Identify the type of embedding.

  • 2% Celloidin for 3 days and subsequent paraffin
  • For large blocks of dense firm tissues (brain)
  • Obsolete
A

Double embedding

35
Q

How much celloidin is used on double embedding?

A

2%

36
Q

Identify the type of embedding.

  • Require dehydration through a graded series of ethyl alcohol, and unless miscible with ethanol
  • Requires the use of a transitional fluid (i.e. clearing agent) such as propylene oxide
A

Epoxy resin

37
Q

What are the most commonly used epoxy resins?

A

Araldite, Epon and Spurr

38
Q

At what temperature does hard blocks are polymerized?

A

60℃

39
Q

What type of knife is used to cut 60-90 nm thick specimens?

A

Diamond knife

40
Q

What type of knife is used to cut 0.5µm thick specimens?

A

Glass knife

41
Q

Identify the type of embedding.

  • Originally introduced for electron microscopy in the mid-1950s
  • Superseded by more superior epoxides
  • Now seldom used
A

Polyester plastics

42
Q

Identify the type of embedding.

  • Made up of esters of acrylic or methacrylic acid
  • used extensively for light microscopy
A

Acrylic plastics

43
Q

What type of acrylic plastic is extremely hydrophilic, allowing many staining methods to be applied, yet tough enough when dehydrated to section well on most microtomes?

A

Polyglycol methacrylate (GMA

44
Q

What type of acrylic plastic is widely used because of its hardness as the ideal embedding medium for undecalcified bone, for bone histomorphometry, and bone marrow hematopathology?

A

Methyl methacrylate (MMA

45
Q

What tissue blocks do not require chilling or refrigeration?

A

Celloidin blocks

46
Q

Identify the blocking-out molds.

  • consists of two L-shaped strips of heavy brass or metal
  • recommended for routine use
  • too slow and cumbersome for use in a busy laboratory
A

Leuckhart’s embedding mold

47
Q

Identify the blocking-out molds.

  • made up of a series of interlocking plates resting on a flat metal base, forming several compartments.
  • has the advantage of embedding more specimens at a time, thereby reducing the time needed for blocking.
A

Compound embedding unit

48
Q

Identify the blocking-out molds.

  • consist of a special stainless steel base mold fitted with a plastic embedding ring, which later serves as the block holder during cutting
  • one of its models is called the Tissue Tek
A

Plastic Embedding Rings And Base Mold

Histopathology (11 decks)

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