P2: Microtomy

Question 1

The process by which processed tissue, most commonly a paraffinembedded tissue, is trimmed and cut into uniformly thin slices known as sections to facilitate studies under the microscope

Answer 1

Microtomy

Question 2

Essential Parts of a Microtome

Answer 2

1. Block Holder
2. Knife carries and knife
3. Pawl, ratchet feed wheel and adjustment screw

Question 3

Where tissues are held in position

Answer 3

Block holder

Question 4

For actual cutting of tissue sections

Answer 4

Knife carrier and knife

Question 5

To line ip the tissue block with the knife, adjusting the thickness of the tissues

Answer 5

Pawl, ratchet feed wheel and adjustment screws

Question 6

Types of Microtome

Answer 6

1. Rocking
2. Rotary
3. Sliding
4. Freezing
5. Ultrathin

Question 7

Used for cutting sections of large blocks of paraffin embedded tissues

Answer 7

Rocking Microtome

Question 8

Rocking microtome is invented by _____

Answer 8

Paldwell Trefall in 1881

Question 9

The simplest among the different types of microtomes

Answer 9

Rocking Microtome

Question 10

Used for cutting sections embedded in paraffin

Answer 10

Rotary Microtome

Question 11

Rotary Microtome was invented by

Answer 11

Minot in 1885-86

Question 12

Most common type used in routine and research laboratories

Answer 12

Rotary Microtome

Question 13

Used for celloidin embedded sections

Answer 13

Sliding Microtome

Question 14

Sliding Microtome was invented by

Answer 14

Adams in 1979

Question 15

Two types of Sliding Microtome

Answer 15

Base sledge
Standard sliding

Question 16

Used for unembedded frozen sections

Answer 16

Freezing Microtome

Question 17

Freezing microtome was invented by

Answer 17

Queckett in 1848

Question 18

Useful in rapid diagnosis and sensitive tissue constituents that are damaged or destroyed by heat

Answer 18

Freezing Microtome

Question 19

A refrigerated apparatus used in fresh tissue microtomy

Answer 19

Cryostat/Cold Microtome

Question 20

Consists of a rotary microtome, kept in cold chamber

Answer 20

Cryostat / Cold Microtome

Question 21

Cryostat is maintained at temperature:

Answer 21

-5 to -30C or (20C average)

Question 22

Useful for rapid preparation of urgent tissue biopsies for intraoperative diagnosis

Answer 22

Cryostat / Cold Microtome

Question 23

Used for cutting tissues in preparation for electron microscopy

Answer 23

Ultrathin Microtome

Question 24

Specific size of Ultrathin Microtome

Answer 24

0.5 micra

Question 25

Knife used in Ultrathin Microtome

Answer 25

Fragments of broken plate glass

Question 26

Specimens in Ultrathin microtome must be:

Answer 26

Small, Fixed in Osmium Tetroxide; embedded in plastic

Question 27

Microtome Knives:

Answer 27

plane concave biconcave plane wedge

Question 28

Size of Plane Concave

Answer 28

25 mm

Question 29

size of biconcave

Answer 29

120 mm

Question 30

size of plane wedge

Answer 30

100 mm

Question 31

One side flat; the other is concave

Answer 31

Plane concave

Question 32

Both sides concave

Answer 32

Biconcave

Question 33

Both sides are straight

Answer 33

Plane wedge

Question 34

Microtome knife used in celloidin-embedded tissues

Answer 34

Plane concave

Question 35

Microtome knife used in paraffin embedded tissues

Answer 35

Biconcave

Question 36

Microtome knife used in Frozen Sections; Extremely hard specimens in paraffin

Answer 36

Plane wedge

Question 37

If not corrected, it will produce tears and striae in tissue sections

Answer 37

Jagged edges

Question 38

Involves the removal of gross nicks on the knife edges (coarse honing)

Answer 38

Honing

Question 39

To remove blemishes, and grinding the cutting edge of the knife on a stone

Answer 39

Honing

Question 40

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

Answer 40

Honing

Question 41

Types of Hones

Answer 41

Belgium yellow Arkansas Fine Carborundum

Question 42

For manual sharpening, for nicked and blunted cutting edges of knife

Answer 42

Belgium yellow

Question 43

Gives more polishing effect than Belgium yellow

Answer 43

Arkansas

Question 44

Much coarser, used for very badly nicked knives

Answer 44

Fine carborundum

Question 45

Honing Procedure:

Answer 45

1. Wipe the surface of the hone with a sift cloth moistened with xylene 2. Cover the hone with mineral of clove oil or soapy water 3. The knife is fitted and with its cutting edge first, the heel is drawn diagonally until the toe, head portion 4. Again with step 3, edge first, with a direction

Question 46

Process of removing the burrs formed during honing and the cutting edge of the knife is polished

Answer 46

Stropping

Question 47

If the knee becomes blunt and dull, but is free from nicks or teeth, it is usually necessary to _____

Answer 47

stropping

Question 48

Procedure of Stropping

Answer 48

1. Use a paddle strop, with good quality horse leather 2. Toe to heel direction, around 40-120 double strokes are usually required

Question 49

Provide the Reason and Remedy for each fault: Brittle or hard tissue

Answer 49

Reason: prolonged fixation, D, C, EM Remedy: Soak tissue in bowl containing water with phenol

Question 50

Provide the Reason and Remedy for each fault: Clearing agent turns milky

Answer 50

Reason: Incomplete dehydration Remedy: Repeat dehydration with absolute alcohol then clear again

Question 51

Provide the Reason and Remedy for each fault: On trimming wax appears crystalline

Answer 51

Reason: Contaminated wax Remedy: Re-embed in freshly filtered wax

Question 52

Provide the Reason and Remedy for each fault: Frozen tissue chips into fragments when cut

Answer 52

Reason: Tissue is frozen too hard Remedy: Warm the tissue with the fingers