FIXATION

Question 1

Post martem devomposition or autolysis occurs due to the action of what enzyme

Answer 1

Hydrolytic enzymes

Question 2

Fixation prevents autolysis by inactivating by what enzyme

Answer 2

Lysosomal enzyme

Question 3

2 types of mechanism

Answer 3

Additive fixation

Non additive fixation

Question 4

Mechanism whereby the chemical constituent of the the fixative is taken in

Forming crosslinks or molecular complexes

Answer 4

Additive fixation

Question 5

Mechanism whereby altering the tissue composition

Upon removal of water to to hbonds, new cross links are established

Acetone and alcohon fixatives are examples

Answer 5

Non-Additive fixation

Question 6

Formalin heated at 60C

Answer 6

Rapid fixation for very urgent biopsy specimens

Question 7

Formalin heated at 100C

Answer 7

For tuberculosis

Question 8

Volume of fixative used

Answer 8

10-25 times the volume of the tissus

Maximum effectiveness
- 20 times the volume of specimen

For museum
- not less than 50-100 times the specime

Question 9

Penetration of fixatives in the tissue at the rate of

Answer 9

1mm/hour

Question 10

Intensifies hematoxylin staining?

Inhibits?

Answer 10

Formaldehyde

Osmium tetroxide

Question 11

Fixative that react with viruses

Answer 11

Mercuric chloride

Question 12

Commonly used fixatives for nucleic acids

Answer 12

MEC

methanol
Ethanol
Carnoys

Question 13

Involves thermal coagulation

For frozen tissue sections (urgent biopsies)

Preparation of bacteriologic smear

Answer 13

Heat fixation

Question 14

Process of placing an already fixed tissue in a second fixative

Acting as a mordant

Answer 14

Secondary fixation

Question 15

Stain MASSON’S TRICHROME

Answer 15

for connective tissue

Question 16

MALLORY’s ANILINE BLUE STAIN

Answer 16

for collagen

Question 17

PHOSPHOTUNGSTIC ACID HEMATOXYLIN

Answer 17

for striated muscles

Question 18

Secondary fixation whereby the primary fixation is placed in Potassium dichromate

Answer 18

Post-chromatization

Question 19

Removing of excess fixative in order to improve staining and remove artifacts

Answer 19

WASHING-OUT

Question 20

Tap water used to remove

Answer 20

COF

chromates
Osmic acid
Formalin

Question 21

Used to remove excess amount of picric acids

Answer 21

50-70% alcohol

Question 22

Used to remove excess mercuric chloride

Answer 22

Alcoholic iodine

Question 23

Fixation is retarded by

Answer 23

Size and thickness
Mucus
Fat
Blood
Cold temp

Question 24

Fixation enhanced by

Answer 24

Size and thickness
Agitation
Heat

Question 25

Volume of fixatives if expensive osmium tetroxide is used

Answer 25

5-10 times the volumes only

Question 26

Floating of air filled organs like lungs may be avoided

Answer 26

Covered with several layer of gauze g

Question 27

Before hollow organs like stomach and intestines immersed, do:

Answer 27

Packed with cotton soaked fixatives

Question 28

What to do to prevent brain from flattening

Answer 28

INTRAVASCULAR PERFUSION

Washing out of bloos with RINGERS LACTATE

Question 29

Hard tissues
-cervix, uterine, fibroids, hyperkeratotic, nails

What u should do? For tissue softener?

Answer 29

LENDRUM’S METHOD

Washed out with running water overnight

Add 4% acqueous phenol solution for 1-3 days

Question 30

Factors considered when choosing the right fixatives

Answer 30

Need for immediate exami
Tissue structure 
Type of tissue
Type of section 
Staining technique

Question 31

For glycogen demontration

Answer 31

Picric acid

Question 32

Glycogen preservation

Glycogen polarization

Answer 32

Alcohol fixative

Question 33

Strong oxidizing agent

Answer 33

Chromic acid

Osmium tetroxide