STEP 4: IMPREGNATION

Question 1

is the simplest, most common and best embedding medium for routine tissue processing

Answer 1

paraffin wax

Question 2

tissue blocks and unstained mounted sections may be
stored for an indefinite period of time after impregnation
without considerable tissue destruction

Answer 2

paraffin wax

Question 3

is not recommended for fatty tissues

Answer 3

paraffin

Question 4

Paraffin oven or incubator at

Answer 4

55-60°C

Question 5

temperature of incubator normally used for routine work

Answer 5

56°C

Question 6

involves wax impregnation under negative atmospheric pressure

Answer 6

vacuum embedding

Question 7

embedding that gives the fastest result; recommended for urgent biopsies

Answer 7

vacuum embedding

Question 8

recommended for delicate tissues such as lung, brain, connective tissues, decalcified bones, eyes, spleen, and central nervous system

Answer 8

vacuum embedding

Question 9

the vacuum chamber of vacuum embedding is maintained at ______ above the melting point of the wax

Answer 9

2-4°C

Question 10

the degree of the vacuum should not exceed ____________

Answer 10

500 mm Hg

Question 11

Factors Affecting Paraffin Wax Impregnation:

Answer 11

1. Natureofthetissue
2. Sizeofthetissue
3. Clearing agents to be used

Question 12

Wax to be reused must be heated at _______

Answer 12

100-105°C

Question 13

Paraffin wax may be used only ______

Answer 13

twice

Question 14

▪ a mixture of highly purified paraffin and synthetic plastic polymers
▪ melting point of 56-57°C
▪ more elastic and resilient than paraffin wax

Answer 14

paraplast

Question 15

• a synthetic wax substitute similar to paraplast with a melting point of 56-58°C
• less brittle, less compressible than paraplast

Answer 15

embeddol

Question 16

• semisynthetic wax recommened for embedding eyes

Answer 16

bioloid

Question 17

• a product of paraffin
• contains rubber
• the same property as paraplast

Answer 17

tissue mat

Question 18

▪ has a lower melting point (46-48°C)
▪ harder than paraffin
▪ cellosolve or xylene may be used as clearing agents
▪ To remove clearing agent: equal portion of clearing agent and wax for 3-6 hours
▪ sectioning of tissues should be done on a heavy duty microtome

Answer 18

ester wax

Question 19

▪ are mostly polyethylene glycols
▪ melting points of 38-42°C or 45-56°C

Answer 19

water soluble waxes

Question 20

▪ most commonly used
▪ solid at room temperature
▪ cytologic details are excellently preserved
▪ very easily dissolved in water
▪ Impregnation: Four changes (70%, 90%, 100%, 100%) at 56°C
▪ Embedding: at 50°C and rapidly cooled in a refrigerator

Answer 20

carbowax

Question 21

▪ a purified form of nitrocellulose soluble in many solvents
▪ suitable for specimens with large hollow cavities
▪ suitable for hard and dense tissues
▪ suitable for large tissue sections of the whole embryo
▪ recommended for processing of neurological tissues
▪ Thin (2%), medium (4%), thick (8%)

Answer 21

celloidin impregnation

Question 22

permits cutiting of tissue sections which are thicker than in paraffin wax

Answer 22

celloidin

Question 23

its rubbery consistency allows tissue blocks to be cut without undue distortio

Answer 23

celloidin

Question 24

impregnation photomicrographs are difficult to obtain

Answer 24

celloidin

Question 25

celloidin impregnation recommended for bones, teeth ,large brain sections, and whole organs

Answer 25

wet celloidin method

Question 26

celloidin impregnation preferred for processing of whole eye sections

Answer 26

dry celloidin method

Question 27

is another form of celloidin soluble in equal concentration of ether and alcohol with a lower
viscosity

Answer 27

Low Viscosity Nitrocellulose (LVN)

Question 28

the tendency of tissues to crack in nitrocellulose method may be prevented by adding _________

Answer 28

plasticizers (oleum ricini or castor oil)

Question 29

▪ is rarely used except when dehydration is to be avoided
▪ used when tissues are subjected to histochemical and enzyme studies
▪ used as an embedding medium for delicate specimens and frozen tissue sections
▪ tissues should not be more than 2-3 mm thick
▪ 1% phenol prevents the growth of molds
▪ The volume of the impregnating medium should be at least 25 times the volume of the tissue

Answer 29

gelatin impregnation