FIXATION

Question 1

The specimen is placed in a liquid fixing agent (fixative) such as ________

Answer 1

FORMALDEHYDE (FORMALIN)

Question 2

It is usually as a phosphate-buffered solution, is the most popular fixative
for preserving tissues that will be processed for paraffin embedding.

Answer 2

FORMALIN

Question 3

The critical step in the preparation of histological sections is ______

Answer 3

FIXATION

Question 4

Following fixation, appropriately trimmed specimens are placed in
suitable ___________ to segregate them from
other specimens.

Answer 4

LABELLED CASSETTES (SMALL PERFORATED BASKETS)

Question 5

Formalin-fixed, paraffin-embedded tissues may be stored indefinitely at ________, and nucleic acids (both DNA and RNA) may
be recovered from them decades after fixation.

Answer 5

ROOM TEMPERATURE

Question 6

A process that preserves tissues from decay, thereby preventing autolysis or putrefaction

Answer 6

FIXATION

Question 7

T/F
Fixation should be carried out as soon as possible after removal of the
tissues (in the case of surgical pathology) or soon after death (in the case of
autopsy) to prevent autolysis.

Answer 7

TRUE

Question 8

T/F
Fixation terminates any ongoing biochemical
reactions, and may also increase the mechanical strength or stability of the
treated tissues.

Answer 8

TRUE

Question 9

T/F
The fixatives employed prevent autolysis by inactivating lysosomal enzymes. They stabilize the fine structure, both inside and between cells, by making macromolecules resistant to dissolution by water and other liquids.

Answer 9

TRUE

Question 10

T/F
Fixatives also inhibit the growth of bacteria and molds that give rise to putrefactive changes.

Answer 10

TRUE

Question 11

T/F
Fixation prevents
degeneration, decomposition, putrefaction, and distortion of tissues after removal from the body.

Answer 11

TRUE

Question 12

______ results from tissue digestion by intracellular enzymes that are released
when organelle membranes rupture.

Answer 12

AUTOLYSIS

Question 13

Bacterial decomposition or ________ is brought about by microorganisms which may already be present in the specimen.

Answer 13

PUTREFACTION

Question 14

________ methods include heating, microwaving and cryo-preservation (freeze drying).

Answer 14

PHYSICAL

Question 15

______ fixation is rarely used on tissue specimens, its application being confined to smears of microorganisms.

Answer 15

HEAT

Question 16

It is regarded as a form of heat fixation, is now widely practiced in routine laboratories

Answer 16

MICROWAVE FIXATION

Question 17

________, usually in the form of freeze drying, has some applications in histochemistry but is not usually applied to diagnostic tissue specimens.

Answer 17

CRYOPRESERVATION

Question 18

_______ fixation is usually achieved by immersing the specimen in the fixative solution (immersion fixation) or, in the case of small animals or some
whole organs such as a lung, by perfusing or injecting the vascular system with fixative (perfusion fixation).

Answer 18

CHEMICAL

Question 19

VAPOR TYPE FIXATIVES are ______, which is used to vapor-fix freeze-dried tissues

Answer 19

PARAFORMALDEHYDE & OSMIUM TETROXIDE

Question 20

_________ whereby the chemical constituent of the fixative is taken in and becomes part of the tissue by forming cross-links or
molecular complexes and giving stability to the protein.

Answer 20

ADDITIVE FIXATION

Question 21

EXAMPLES OF ADDITIVE FIXATION

Answer 21

FORMALIN, MERCURY, & OSMIUM TETROXIDE

Question 22

________ whereby the fixing agent is not incorporated
into the tissue, but alters the tissue composition and stabilizes the tissue
by removing the bound water attached to H-bonds of certain groups
within the protein molecule.

Answer 22

NON-ADDITIVE FIXATION

Question 23

Fixative solutions may contain a single fixative agent dissolved in a solvent
such as _______ or _______ or more commonly, a buffer solution to stabilize pH.

Answer 23

WATER or ALCOHOL

Question 24

Specimens should be transferred to fixative quickly _______ after
surgery as deterioration will commence with the loss of blood supply.

Answer 24

LESS THAN 1 HOUR

Question 25

Tissues should be fixed in a sufficient volume of solution; generally in a ratio of ____ or at least ____ fixative to specimen, for penetration to occur in the most efficient manner.

Answer 25

20:1 or at least 10:1

Question 26

Anatomical barriers to fixation must be _______ or _______ (e.g. fascia, bone, feces, thick tissue)

Answer 26

REMOVED or INCISED

Question 27

large specimens must be ______ or ______ with fixative (e.g. lung) or opened and cleaned (gastrointestinal tract) to allow penetration.

Answer 27

SECTIONED or INFLATED

Question 28

The volume of fixative is important. Traditionally, the amount of fixative used has been ______ the volume of tissue to be fixed.

Answer 28

10-20 times

Question 29

Fixation is best carried out close to _______ pH, in the range of ______

Answer 29

NEUTRAL pH (6-8)

Question 30

Commercial formalin is buffered with phosphate at a _______

Answer 30

pH of 7

Question 31

Many laboratories use tissue processors that work at ______ for regular tissue processing.

Answer 31

40C

Question 32

For electron microscopy and some histochemistry, the ideal temperature is ______

Answer 32

0-4C

Question 33

Formalin heated to ____ is sometimes used for the rapid fixation of very urgent biopsy specimens, although the risk of tissue distortion is increased.

Answer 33

60C

Question 34

Electron Microscopy tissue blocks size should be ______

Answer 34

1-2mm^2

Question 35

Light Microscopy tissue blocks size should be ______

Answer 35

2cm^2 wide

Question 36

Brain is usually suspended whole in _________ to ensure fixation and some hardening prior to sectioning.

Answer 36

10% buffered formalin for 2-3 weeks

Question 37

For solid material (e.g., liver) the longest dimension should not exceed ______

Answer 37

10-15mm

Question 38

HYPERTONIC = _______

Answer 38

SHRINKS

Question 39

HYPOTONIC = ________

Answer 39

SWELL & BURST