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Histopath LEC > MICROTOMY part 2 > Flashcards

MICROTOMY part 2 Flashcards

1
Q

TYPES OF TISSUE SECTIONS

A

Paraffin
Celloidin
Frozen sections

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2
Q

Paraffin section size

A

4-6 um

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3
Q

Successive sections will usually stick edge-to-edge.

A

Paraffin section

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4
Q

Sections are removed in ribbons of ten to allow easy location of serial sections.

Most common

A

Paraffin sections

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5
Q

Celloidin section size

A

10-15um

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6
Q

The blocks are trimmed in the same manner as in paraffin blocks.

To avoid dehydration and shrinkage, sections are usually cut by the wet method, with both the sections and the block being kept moist with _____during cutting.

A

Celloidin

70% alcohol

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7
Q

_____sections do not come off in ribbons and have to be collected into 70% alcohol immediately.

A

Celloidin

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8
Q

Frozen Sections

Methods of preparing frozen section:

A
  1. Cold knife procedure
  2. Cryostat procedure (cold microtome)
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9
Q

three basic types or shapes of microtome knives:

A

Plane-concave knife
Bioconcave knife
Plane-wedge knife

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10
Q

Plane-Concave Knife (usually_____. in length)

A

25 mm

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11
Q

Biconcave Knife (usually____. in length)

A

120 mm

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12
Q

Plane-Wedge Knife (usually____. in length)

A

100 mm

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13
Q

One side of the knife is flat while the other is concave.

A

Plane concave knife

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14
Q

Less concave sides are recommended for cutting_______-embedded tissue blocks on a______ microtome.

A

celloidin

sliding

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15
Q

More concave sides are used to cut_____ sections on base-sledge, rotary or rocking microtome

A

paraffin

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16
Q

with both sides concave

A

Biconcave

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17
Q

Biconcave knife

recommended for cutting_____ - embedded sections on a_____ microtome.

A

paraffin

rotary

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18
Q

have both sides straight

A

Plane-wedge knife

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19
Q

Plane-wedge knife

recommended for______ sections or for cutting extremely hard and tough specimens embedded in_____ blocks, using a_____ or _____

A

frozen

paraffin

base sledge type or sliding microtome.

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20
Q

recommended for frozen sections or for cutting extremely hard and tough specimens embedded in paraffin blocks, using a base sledge type or sliding microtome.

A

Plane-wedge knife

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21
Q

_____ and _____ knives are usually provided with backs, to maintain the correct bevel angle throughout honing.

Detachable handles may be attached to the knife during sharpening.

A

Plane-wedge and plane-concave

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22
Q

The angle formed between the cutting edges is known as the “______”, normally about________

A

Bevel angle

27° to 32°

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23
Q

Too______ cutting edges are likely to become dull easily, while too____ edges are likely to produce nicks or jagged edges and irregularities on the knife edge, thereby producing tears or striation on the tissue sections during cutting.

A

soft

hard

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24
Q

A good cutting edge must be able to cut good sections from a paraffin wax block about_______ thick, without any serration noted on examination.

A

2-3 microns

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25
Q

________may be used for partially calcified materials, paraffin and frozen sections.

They are readily replaced when dull, and produce similarly good tissue sections as those cut with microtome knives

A

Safety razor blades

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26
Q

unsatisfactory for sections less than 10 µ

A

Safety razor blades

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27
Q

Theoretically, the perfect and optimum cutting angle is obtained when the sides of the wedge knife are inclined at an angle of about_____, causing maximum penetration of the tissues and minimizing distortion

A

15°

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28
Q

To prevent uneven sections, or alternate thin and thick sections, the knife should be inclined with a ______ clearance angle from the cutting plane so that the cutting facet will not compress the block during the process of cutting

A

5-10°

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29
Q

True or False

The cutting edge must be thinner than the section being cut.

A

True

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30
Q

A good cutting edge must be sharp enough to cut good sections from a paraffin wax block at____ thick without causing serrations.

A

4 µ

31
Q

OTHER KNIVES AND BLADES

A

Disposable blades
Glass knives/ Ralph knives
Diamond knives
Safety razor blades

32
Q

• Widely used now because cheaper;
• Honing and stropping are no longer common practices;

A

Disposable Blades

33
Q

Disposable Blades

Coated with_______ (for ease of ribboning).

A

polytetrafluoroethylene

34
Q

• For ultrathin microtomes.

A

Glass Knives/ Ralph Knives

35
Q

• For resin blocks on ultrathin microtomes;
• Brittle and expensive

A

Diamond knives

36
Q

For partially calcified materials, paraffin, and frozen sections.

A

Safety razor blades

37
Q

Safety Razor Blades

Unsatisfactory for sections less than____

A

10 micro.

38
Q

Badly Nicked knives with blunted ends have to undergo_____ in order to ensure optimum sectioning of tissue blocks.

A

sharpening

39
Q

Sharpening of the knives involves 2 stages, namely:

A

Honing
Stropping

40
Q

HONING

A

Removing of gross nicks
To acquire an even edge
HEEL to TOE

41
Q

STROPPING

A

Removal of burr/irregularities
Final polishing of the knife edge
TOE to HEEL

42
Q

Hard sharpening

A

Honing

43
Q

Honing involves the removal of gross nicks on the knife edge (_______) to remove blemishes

grinding the cutting edge of the knife on a stone (_______) to acquire an even edge

A

Coarse Honing

Honing Proper

44
Q

The degree of sharpness is proportional to the fineness of the abrasive used in sharpening

A

Honing

45
Q

This procedure makes use of a______, a natural sharpening stone or hard grinding surface (carborundum), which serves to remove nicks and irregularities on the knife edges.

A

hone

46
Q

Several types of hones may be used:

A

Belgium yellow
Arkansas
Fine carborundum

47
Q
  • for manual sharpening when cutting edge has been rendered blunt or nicked.

This type usually gives the best result.

MOST COMMON

A

Belgium Yellow

48
Q
  • gives more polishing effect than the Belgium Yellow.
A

Arkansas

49
Q
  • is much coarser than the first two types and is used only for badly nicked knives followed by either one of the first two knife sharpeners.

EXCELLENT

A

Fine carborundum

50
Q

The surface of the hone is wiped clean with a soft cloth moistened with_____ in order to remove the scattered small particles of stones and metal

A

xylene

51
Q

Honing lubricants

A

• Soapy water
• Mineral oil
• Clove oil
• Xylene
• Liquid paraffin

52
Q

Honing

The knife is fitted to its corresponding back, placed on one end of the hone, and with the cutting knife edge first,

the “____” (handle end) is drawn obliquely or diagonally towards the operator on the stone until the “____” (head portion) is reached.

A

heel

toe

53
Q

The knife is then turned over, and the other surface is again drawn forward, EDGE FIRST, with a HEEL TO TOE direction.

A

Honing

54
Q

In the case of the Minot or plane-wedge knife, the knife is turned over so as to sharpen the other surface every_____ strokes

A

I0-20

55
Q

Honing

For plane-concave knives, only the_____ surface should be rubbed on the Hone.

A

concave

56
Q

Honing

______may also be used for final polishing

A

Diamantine

57
Q

Mechanical honing with machines may make use of a vibrating frosted glass plate or a wheel driven by an electrical motor.

The knife is pressed against the flat side of a rotating glass wheel which is being driven by a mechanical device.

Approximately____\ double strokes are given each side of the knife to which very gentle pressure is applied.

The use of knife sharpening machines, although quite expensive, is usually time-saving and produce well sharpened knives with uniform bevels

A

30

58
Q

The hone should be long enough (about______) to allow the whole length of the knife edge to be sharpened in a single stroke and wide enough to sufficiently support and prevent the rocking of the knife.

A

8” x 3”

59
Q

is the process whereby the “burr” formed during honing is removed and the cutting edge of the knife is polished.

A

Stropping

60
Q

The purpose of______ is to polish and sharpen the cutting edge, while that of______ is to remove the irregularities from the knife.

A

stropping

honing

61
Q

If the knife has become dull and blunt, but is free from nicks or teeth, it is usually only necessary to____ it.

For delicate work, the knife is____ before every object is sectioned.

A

strop; stropped

62
Q

A paddle strop made up of the best quality_______, firmly attached to a solid back, in order to prevent sagging is preferred

A

horse leather

63
Q

e procedure is the reverse of honing.

A

Stropping

64
Q

The knife is first fitted with its appropriate knife back, then laid obliquely on the strop and with the cutting edge behind, (EDGE LAST) is pushed backward and drawn forward in a TOE TO HEEL direction

A

Stropping

65
Q

In stropping

Around______ double strokes are usually required.

A

40-120

66
Q

Stropping

…applied on the back of the horse leather;

Not _____because it tends to blister and the leather destroys.

A

Vegetable oil (e.g. castor oil)

mineral oil

67
Q

The strop should not be used for at least ______ after treatment.

Too much oil will make the stropping surface slippery and will render the procedure unsatisfactory.

To remove excessive oil from the strop, its surface is scraped with a_____

A

24-48 hours

blunt instrument, e.g. the back of the knife.

68
Q

Wax must not be allowed to come in contact with the strop. With an applicator, the used knife blade should be washed and flushed with_____

A

xylene

69
Q

Disposable blades

They have a sharp cutting edge that can cut_____ thick sections with ease.

A

2-4 µ

70
Q

are also now available that can attach to some blade holders and are particularly suitable for use in the cryostat.

A

Magnetic knives

71
Q

are generally used for trimming and semi-thin sectioning of tissue blocks for electron microscopy.

A

Glass knives

72
Q

are used to cut any type of resin block for electron microscopy.

When supplied by manufacturers, they are already mounted in a metal block designed to fit directly into the knife holder of the ultrathin microtome

A

Diamond knives

73
Q

.
Used for adhesion of the tissue to be examined to the slide.
.
For: Brain sections, decalcified tissue, and when using strong alkali at time of staining.

A

ADHESIVES

74
Q

ADHESIVES examples

A

• Mayer’s Egg Albumin
• Dried albumin
• Starch paste
• Plasma
• 1% Gelatin
• 1% Methyl Cellulose
• Poly-L Lysine
• Sodium silicate
• Resins

Histopath LEC (37 decks)

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