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Histopath Lec > Microtomy > Flashcards

Microtomy Flashcards

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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
Thickness of microtome
3-5 um
25
Who developed sliding microtome
Adams in 1789
26
Especially recommended for cutting extremely hard and rough tissue blocks
Sliding microtome
27
28
Most dangerous type of microtomedue to the movable exposed knife
Sliding microtome
29
Consists of two movable pillars holding the adjustable knife clamps, allowing the knife to be set an angle for cutting celloidin sections
Base sledge microtome
30
The block remains stationary while the knife is moved backward and forward during the process of sectioning
Standard sliding microtome
31
Originally designed for cutting sections of very large blocks (whole brain)
Base sledge microtome
32
Who invented freezing microtome
Queckett in 1848
33
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
Freezing microtome
34
used to cut undehydrated thin to semi-thin sections of fresh, frozen tissues
Freezing microtome
35
Freezing microtome is used in
- 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
36
Give the best results and is used almost universally
Freezing microtome
37
It consists of a microtome, usually a rotary microtome, kept inside a cold chamber
Cryostat or cold microtome
38
Temperature of cryostat
-15 to -30 (ave is -20)
39
Thickness of cryostat microtome
4 u
40
means of preparing thin sections of fresh frozen tissues especially for fluorescent antibody staining techniques or histochemical enzyme studies
Cryostat microtome
41
most commonly used for rapid preparation of urgent tissue biopsies for intraoperative diagnosis.
Cryostat microtome
42
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
ultrathin microtome
43
Sections are usually transferred directly from the microtome knife to a slide or cover glass, all of which are maintained at a low temperature
Cryostat microtome
44
Thickness of ultrathin microtome
0.5 to 1 um
45
Microtome knives
Plane-Concave Biconcave Plane wedge
46
Knives for electron microscope
Glass knives Diamond knives Disposable blade
47
Length of plane-concave
25 mm
48
Length of biconcave
120 mm
49
– for celloidin embedded tissue block on sliding microtome
Less concave
50
paraffin sections on base-sledge, rotary, rocking microtome
More concave
51
For paraffin embedded section on a rotary microtome
Biconcave
52
For extremely hard and tough specimen embedded in paraffin, using a base sledge type or sliding microtome
Plane - wedge
53
the angle formed between the cutting edges normally about
27-32 °
54
Perfect and optimum angle is obtained when the sides of the wedge knife are inclined at an angle of about
15°
55
Size of glass knives
40x25 cm
56
Used for trimming and semi-thin sectioning of tissue block
Glass knives
57
Used to cut any type of resin block
Diamond knives
58
Cheaper to use than conventional steel knives
Disposable blades
59
Brittle and expensive, but very durable
Diamond knives
60
Disposable blade can cut _____ um thick sections
2-4
61
removal of gross nicks to remove blemishes, grinding the cutting edge of the knife on a stone
Honing
62
Types of hone
Belgium yellow Arkansas Fine carborundum
63
For manual sharpening Provides best result
Belgium yellow
64
Much coarser Used only for badly nicked knives followed by either one of the first two knife sharpeners
Fine carborundum
65
Gives more polishing effect
Arkansas
66
the process whereby the “burr” formed during honing is removed and cutting edge of the knife is polished
Stropping (toe to heel)
67
Purpose of stropping
Polish and sharpen the cutting edge
68
Purpose of honing
Remove irregularities from the knife
69
Process whereby tissues are cut into uniformly thin slices or “sections” with the aid of a microtome, to facilitate the studies under the microscope
Cutting sections
70
General Types of Tissue Sections
Paraffin section Celloidin section Frozen section
71
For paraffin embedded tissue blocks which may be cut by _____
rocking and rotary microtome
72
For celloidin embedded tissues which are usually cut by means of the
sliding microtome
73
Frozen Sections may cut tissues that have been
fixed and frozen with CO2 or for fresh or fixed and frozen with the cryostat
74
Factors to be Considered in Sectioning
* Cutting depend upon the type of the tissue * The size of the block * The model or the type of the microtome
75
Sections usually in thickness for routine histologic procedure
4-6μ
76
Temperature for waterbath
5-10° below the melting point
77
Size of slides
76 x 25 mm slides that are 1.0- 1.2 mm
78
A section is selected for staining and picked up onto a clean slide in a vertical position
Floating Out
79
Temperature of the water bath during floating out
45 -50°C, approximately 6- 10°C lower than the melting point of the wax used for embedding the tissue
80
substances which can be smeared on to the slides so that the sections stick well to the slides.
ADHESIVES
81
not necessary for routine staining
Adhesive
82
Adhesive is essential for methods that require exposure of sections to
acids and alkalis
83
Section can fixed to the slides
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
Why does delicate tissues need to be in low temperature?
To avoid splitting and cracking of section due to excessive heat
85
Instances when sections may float from the slide and adhesive are necessary
* 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
Common Adhesives Used
- Mayer's egg albumin - dried albumin - gelatin - starch paste - plasma
87
Component of Mayer's egg albumin
Glycerin Egg white Thymol Crystals
88
Component of dried albumin
Sodium chloride Dry albumin Thymol crystals
89
Component of gelatin
Gelatin 1 gm Glycerol 15 ml Phenol crystal 2 gm dissolved in DW 100 ml
90
Component of starch paste
Powdered starch 2 drops of hydrochloric acid Thymol crystals
91
This is widely used as a section adhesive in immunohistochemistry
Poly-L-lysine
92
Concentration of poly-L-lysine
0?1% solution which is further diluted in 1:10 DW
93
Final dilution of poly-L-lysine
0.01%
94
APES-coated slides are very useful in cytology, particularly for cytospin preparations of proteinaceous or bloody material
3-aminopropylthriethoxysilane
95
Advantage of 3-aminopropylthriethoxysilane
can be stored for a long time without losing their adhesiveness
96
most commonly used because it is very easy to make, is convenient, and is relatively inexpensive.
Mayer's Egg Albumin
97
Composition of gelatin formaldehyde mixture
* 1% gelatin 5 ml * 2% formaldehyde 5 ml

Histopath Lec (14 decks)

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