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Histopath Lec > Microtomy > Flashcards

Microtomy Flashcards

1
Q

a skilled process that requires
precision and hand - eye coordination combine
with a delicate touch by the experience
histotechnologist/cian

A

Microtomy

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2
Q

The basic instrument that is capable of cutting a section at a
predetermined thickness by sliding the block into a cutting tool, usually a
steel knife, glass or diamond blade, which is fixed and attached to the
machine.

A

Microtome

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3
Q

Important parts of microtome

A
  1. Block holder
  2. Knife carrier and knife
  3. Pawl, ratchet feed wheel and adjustment screws
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4
Q

for actual cutting of tissue sections

A

Knife carrier and knife

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5
Q

To line up the tissue
block in proper position with the knife, adjusting the proper thickness of the
tissue for successive sections.

A

Pawl, ratchet feed wheel and adjustment screws

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6
Q

where the tissue is held in position

A

Block holder

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7
Q

What is the principle of microtome

A

a spring-balanced teeth or pawl is brought into contact
with, and turns a ratchet feed wheel connected to a
micrometer screw, which is in turn rotated, moving the
tissue block at a predetermined distance towards the
knife for cutting sections at uniform thickness.

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8
Q

Types of microtome

A
  1. Rocking microtome
  2. Rotary microtome
  3. Sliding microtome
  4. Freezing microtome
  5. Cryostat or cold microtome
  6. Ultrathin microtome
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9
Q

for cutting serial sections of large blocks of
paraffin embedded tissues.

A

Rocking microtome

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10
Q

for cutting sections for Electron Microscopy.

A

Ultrathin microtome

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11
Q

for cutting celloidin embedded sections.

A

Sliding microtome

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12
Q

for cutting frozen section

A

Cryostat or cold microtome

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13
Q

for cutting paraffin embedded sections

A

Rotary microtome

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14
Q

-for cutting unembedded frozen sections.

A

Freezing microtome

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15
Q

Who invented rocking microtome

A

Paldwell Trefall in 1881

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16
Q

Thickness of rocking microtome

A

10-12 u

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16
Q

simplest
among the different types of microtome

A

Rocking (Cambridge) Microtome

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17
Q

Disadvantage of rocking microtome

A
  • restriction in size of tissue block
  • difficulty of reorienting the block
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18
Q

Who invented rotary microtome

A

Minot in 1885-1886

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19
Q

currently the
most common type used for both routine and
research laboratories, especially for sectioning
paraffin-embedded tissues

A

Rotary microtome

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20
Q

available in
two sizes, has been used to cut small and large
block of paraffin tissues

A

Rocking microtome

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21
Q

Two types of sliding microtome

A
  • base sledge microtome
  • standard sliding microtome
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22
Q

Used for routine and research laboratories

A

Rotary microtome

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23
Q

Electrically driven rotary microtomes are also now
available and can be ideally used to produce
ribbons for serial sections

A

Rotary microtome

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24
Q

Thickness of microtome

A

3-5 um

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25
Q

Who developed sliding microtome

A

Adams in 1789

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26
Q

Especially recommended for cutting extremely
hard and rough tissue blocks

A

Sliding microtome

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27
Q
A
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28
Q

Most dangerous type of microtomedue to the
movable exposed knife

A

Sliding microtome

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29
Q

Consists of two
movable pillars holding the adjustable knife
clamps, allowing the knife to be set an angle for
cutting celloidin sections

A

Base sledge microtome

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30
Q

The block
remains stationary while the knife is moved
backward and forward during the process of
sectioning

A

Standard sliding microtome

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31
Q

Originally designed for cutting sections of
very large blocks (whole brain)

A

Base sledge microtome

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32
Q

Who invented freezing microtome

A

Queckett in 1848

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33
Q

The stage for block holder is hollow and perforated
around its perimeter, attached to a reinforced
flexible lead pipe thru which carbon dioxide
passes from a cylinder

A

Freezing microtome

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34
Q

used to cut undehydrated thin to semi-thin
sections of fresh, frozen tissues

A

Freezing microtome

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35
Q

Freezing microtome is used in

A
  • rapid diagnosis is required
  • histological demonstration of fat is needed
  • certain neurological structures are to be studied
  • sensitive tissue constituent to be studied is damaged or destroyed by heat
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36
Q

Give the best results and is used almost
universally

A

Freezing microtome

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37
Q

It consists of a microtome, usually a rotary
microtome, kept inside a cold chamber

A

Cryostat or cold microtome

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38
Q

Temperature of cryostat

A

-15 to -30 (ave is -20)

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39
Q

Thickness of cryostat microtome

A

4 u

40
Q

means of preparing thin sections of
fresh frozen tissues especially for fluorescent antibody staining
techniques or histochemical enzyme studies

A

Cryostat microtome

41
Q

most commonly used for rapid preparation of urgent tissue
biopsies for intraoperative diagnosis.

A

Cryostat microtome

42
Q

equipped with a glass or gem grade diamond knife is used to cut
very thin sections (typically 60 to 100 nanometer) of tissue embedded in epoxy resin

A

ultrathin microtome

43
Q

Sections are usually transferred directly from the
microtome knife to a slide or cover glass, all of
which are maintained at a low temperature

A

Cryostat microtome

44
Q

Thickness of ultrathin microtome

A

0.5 to 1 um

45
Q

Microtome knives

A

Plane-Concave
Biconcave
Plane wedge

46
Q

Knives for electron microscope

A

Glass knives
Diamond knives
Disposable blade

47
Q

Length of plane-concave

A

25 mm

48
Q

Length of biconcave

A

120 mm

49
Q

– for celloidin embedded
tissue block on sliding microtome

A

Less concave

50
Q

paraffin sections on base-sledge,
rotary, rocking microtome

A

More concave

51
Q

For paraffin embedded section on a rotary
microtome

A

Biconcave

52
Q

For extremely hard and tough specimen
embedded in paraffin, using a base sledge type or
sliding microtome

A

Plane - wedge

53
Q

the angle formed between the
cutting edges normally about

A

27-32 °

54
Q

Perfect and optimum angle is obtained when
the sides of the wedge knife are inclined at an
angle of about

A

15°

55
Q

Size of glass knives

A

40x25 cm

56
Q

Used for trimming and semi-thin sectioning of
tissue block

A

Glass knives

57
Q

Used to cut any type of resin block

A

Diamond knives

58
Q

Cheaper to use than conventional steel knives

A

Disposable blades

59
Q

Brittle and expensive, but very durable

A

Diamond knives

60
Q

Disposable blade can cut _____ um thick sections

A

2-4

61
Q

removal of gross nicks to remove
blemishes, grinding the cutting edge of the knife
on a stone

A

Honing

62
Q

Types of hone

A

Belgium yellow
Arkansas
Fine carborundum

63
Q

For manual sharpening
Provides best result

A

Belgium yellow

64
Q

Much coarser
Used only for badly nicked knives followed by
either one of the first two knife sharpeners

A

Fine carborundum

65
Q

Gives more polishing effect

A

Arkansas

66
Q

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

A

Stropping (toe to heel)

67
Q

Purpose of stropping

A

Polish and sharpen the cutting edge

68
Q

Purpose of honing

A

Remove irregularities from the knife

69
Q

Process whereby tissues are cut into uniformly
thin slices or “sections” with the aid of a
microtome, to facilitate the studies under the
microscope

A

Cutting sections

70
Q

General Types of Tissue Sections

A

Paraffin section
Celloidin section
Frozen section

71
Q

For paraffin embedded tissue blocks which may
be cut by _____

A

rocking and rotary microtome

72
Q

For celloidin embedded tissues which are usually
cut by means of the

A

sliding microtome

73
Q

Frozen Sections
may cut tissues that have been

A

fixed and frozen with CO2 or for fresh or fixed and
frozen with the cryostat

74
Q

Factors to be Considered in Sectioning

A
  • Cutting depend upon the type of the tissue
  • The size of the block
  • The model or the type of the microtome
75
Q

Sections usually in thickness for routine
histologic procedure

A

4-6μ

76
Q

Temperature for waterbath

A

5-10° below the melting point

77
Q

Size of slides

A

76 x 25 mm slides that are 1.0-
1.2 mm

78
Q

A section is selected for
staining and picked up onto a
clean slide in a vertical
position

A

Floating Out

79
Q

Temperature of the water bath during floating out

A

45 -50°C, approximately 6- 10°C lower than the melting
point of the wax used for
embedding the tissue

80
Q

substances which can be
smeared on to the slides so
that the sections stick well to
the slides.

A

ADHESIVES

81
Q

not necessary for routine
staining

A

Adhesive

82
Q

Adhesive is essential for methods that
require exposure of sections to

A

acids and alkalis

83
Q

Section can fixed to the slides

A

37C incubator overnight
Wax oven at 56-60C for 2 hrs
Drying on a hot plate at 45-55 for 30-45 mins

For delicate tissues like CNS or brain 37C for 24 hrs or longer

84
Q

Why does delicate tissues need to be in low temperature?

A

To avoid splitting and cracking of section due to excessive heat

85
Q

Instances when sections may float from the slide and adhesive are necessary

A
  • Urgent cryostat sections to be submitted for
    immunocytochemistry
  • Central nervous system tissues
  • Tissues containing blood clot
  • Tissues which have been decalcified
  • When sections are to be subjected to high temperatures
86
Q

Common Adhesives Used

A
  • Mayer’s egg albumin
  • dried albumin
  • gelatin
  • starch paste
  • plasma
87
Q

Component of Mayer’s egg albumin

A

Glycerin
Egg white
Thymol Crystals

88
Q

Component of dried albumin

A

Sodium chloride
Dry albumin
Thymol crystals

89
Q

Component of gelatin

A

Gelatin 1 gm
Glycerol 15 ml
Phenol crystal 2 gm
dissolved in DW 100 ml

90
Q

Component of starch paste

A

Powdered starch
2 drops of hydrochloric acid
Thymol crystals

91
Q

This is widely used as a section adhesive in
immunohistochemistry

A

Poly-L-lysine

92
Q

Concentration of poly-L-lysine

A

0?1% solution which is further diluted in 1:10 DW

93
Q

Final dilution of poly-L-lysine

A

0.01%

94
Q

APES-coated slides are very useful in cytology,
particularly for
cytospin preparations of
proteinaceous or bloody material

A

3-aminopropylthriethoxysilane

95
Q

Advantage of 3-aminopropylthriethoxysilane

A

can be stored for a long time without losing
their adhesiveness

96
Q

most commonly used because it is very easy to make, is
convenient, and is relatively inexpensive.

A

Mayer’s Egg Albumin

97
Q

Composition of gelatin formaldehyde mixture

A
  • 1% gelatin 5 ml
  • 2% formaldehyde 5 ml

Histopath Lec (7 decks)

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