MICROTOMY part 2

Question 1

TYPES OF TISSUE SECTIONS

Answer 1

Paraffin
Celloidin
Frozen sections

Question 2

Paraffin section size

Answer 2

4-6 um

Question 3

Successive sections will usually stick edge-to-edge.

Answer 3

Paraffin section

Question 4

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

Most common

Answer 4

Paraffin sections

Question 5

Celloidin section size

Answer 5

10-15um

Question 6

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.

Answer 6

Celloidin

70% alcohol

Question 7

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

Answer 7

Celloidin

Question 8

Frozen Sections

Methods of preparing frozen section:

Answer 8

1. Cold knife procedure
2. Cryostat procedure (cold microtome)

Question 9

three basic types or shapes of microtome knives:

Answer 9

Plane-concave knife
Bioconcave knife
Plane-wedge knife

Question 10

Plane-Concave Knife (usually_____. in length)

Answer 10

25 mm

Question 11

Biconcave Knife (usually____. in length)

Answer 11

120 mm

Question 12

Plane-Wedge Knife (usually____. in length)

Answer 12

100 mm

Question 13

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

Answer 13

Plane concave knife

Question 14

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

Answer 14

celloidin

sliding

Question 15

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

Answer 15

paraffin

Question 16

with both sides concave

Answer 16

Biconcave

Question 17

Biconcave knife

recommended for cutting_____ - embedded sections on a_____ microtome.

Answer 17

paraffin

rotary

Question 18

have both sides straight

Answer 18

Plane-wedge knife

Question 19

Plane-wedge knife

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

Answer 19

frozen

paraffin

base sledge type or sliding microtome.

Question 20

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

Answer 20

Plane-wedge knife

Question 21

_____ 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.

Answer 21

Plane-wedge and plane-concave

Question 22

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

Answer 22

Bevel angle

27° to 32°

Question 23

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.

Answer 23

soft

hard

Question 24

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

Answer 24

2-3 microns

Question 25

________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

Answer 25

Safety razor blades

Question 26

unsatisfactory for sections less than 10 µ

Answer 26

Safety razor blades

Question 27

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

Answer 27

15°

Question 28

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

Answer 28

5-10°

Question 29

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

Answer 29

True

Question 30

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

Answer 30

4 µ

Question 31

OTHER KNIVES AND BLADES

Answer 31

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

Question 32

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

Answer 32

Disposable Blades

Question 33

Disposable Blades Coated with_______ (for ease of ribboning).

Answer 33

polytetrafluoroethylene

Question 34

• For ultrathin microtomes.

Answer 34

Glass Knives/ Ralph Knives

Question 35

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

Answer 35

Diamond knives

Question 36

For partially calcified materials, paraffin, and frozen sections.

Answer 36

Safety razor blades

Question 37

Safety Razor Blades Unsatisfactory for sections less than____

Answer 37

10 micro.

Question 38

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

Answer 38

sharpening

Question 39

Sharpening of the knives involves 2 stages, namely:

Answer 39

Honing Stropping

Question 40

HONING

Answer 40

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

Question 41

STROPPING

Answer 41

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

Question 42

Hard sharpening

Answer 42

Honing

Question 43

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

Answer 43

Coarse Honing Honing Proper

Question 44

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

Answer 44

Honing

Question 45

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.

Answer 45

hone

Question 46

Several types of hones may be used:

Answer 46

Belgium yellow Arkansas Fine carborundum

Question 47

- for manual sharpening when cutting edge has been rendered blunt or nicked. This type usually gives the best result. MOST COMMON

Answer 47

Belgium Yellow

Question 48

- gives more polishing effect than the Belgium Yellow.

Answer 48

Arkansas

Question 49

- 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

Answer 49

Fine carborundum

Question 50

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

Answer 50

xylene

Question 51

Honing lubricants

Answer 51

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

Question 52

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.

Answer 52

heel toe

Question 53

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

Answer 53

Honing

Question 54

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

Answer 54

I0-20

Question 55

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

Answer 55

concave

Question 56

Honing ______may also be used for final polishing

Answer 56

Diamantine

Question 57

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

Answer 57

30

Question 58

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.

Answer 58

8" x 3"

Question 59

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

Answer 59

Stropping

Question 60

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

Answer 60

stropping honing

Question 61

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.

Answer 61

strop; stropped

Question 62

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

Answer 62

horse leather

Question 63

e procedure is the reverse of honing.

Answer 63

Stropping

Question 64

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

Answer 64

Stropping

Question 65

In stropping Around______ double strokes are usually required.

Answer 65

40-120

Question 66

Stropping …applied on the back of the horse leather; Not _____because it tends to blister and the leather destroys.

Answer 66

Vegetable oil (e.g. castor oil) mineral oil

Question 67

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_____

Answer 67

24-48 hours blunt instrument, e.g. the back of the knife.

Question 68

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_____

Answer 68

xylene

Question 69

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

Answer 69

2-4 µ

Question 70

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

Answer 70

Magnetic knives

Question 71

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

Answer 71

Glass knives

Question 72

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

Answer 72

Diamond knives

Question 73

. 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.

Answer 73

ADHESIVES

Question 74

ADHESIVES examples

Answer 74

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