Microtomy Flashcards
The angle formed between the block and the cutting facet of a knife is known as the:
clearance angle
which of the following embedding procedures involves first infiltrating the tissue with one medium and then embedding it with another?
a. double
b. resin
c. routine
d. vacuum
a. double embedding
for friable tissue or multiple fragments: infiltrate in gelatin and embedding in agar
When frozen sections stick to a cryostat anti-roll plate, the plate is:
too warm
To remove grit and dirt before embedding, paraffin may have to be:
a. filtered
b. heated
c. solidified
d. washed
a. filtered
it is important that the faced of a cryostat knife be small to prevent:
a. loose metal shavings from attaching to the sections
b. problems with the anti-roll plate
c. the section from curling as it is cut
d/ the venetian blind effect
b. problems with the anti-roll plate
Microscopic examination of an H&E section reveals marked background stainings. This is caused by:
a. albumin spread on the slide by a finger
b. excess section adhesive on the slide
c. sections being taken immediately after rough facing the block
d. the flotation bath not being cleaned between blocks
b. excess section adhesive on the slide
when frozen sections appear above the anti-roll plate of a cryostat, the plate is:
too far below the knife edge
during sectioning of a block of uterine tissue, alternate thick and thin zones are observed, this is caused by:
a. improper embedding
b. inadequate processing
c. vibration of the knife
d. non-parallel block edges
c. vibration of the knife
which tissue should be sectioned at 3um?
a. brain
b. breast
c. liver
d. lymph node
d. lymph node
sections are being lifted from the knife on the upstroke. This is probably because the:
a. knife is too sharp
b. knife tilt is incorrect
c. paraffin is too cold
d. specimen is too hard
b. knife tilt is incorrect
when frozen sections partially jam and partially slide under the anti-roll plate, the plate is:
Not parallel to the knife edge
which if the following groups of plates may be used to support abrasive powders and lubricants for sharpening knives?
a. copper, glass, iron
b. aluminum, copper, glass
c. copper, iron, aluminum
d. glass, aliminum , iron
b. aluminum, copper, glass
never iron! it rusts too quickly
which of the following could be substituted for gelatin as an additive to the flotation bath?
a. aminoalkylsilane b. chromium potassium sulfate
c. poly L-Lysine
d. agar
d. agar
for flotation bath: agan, gelatin and Elme’s glue
A finger nail has been fixed in formalin, processed and embedded in paraffin. The tissue is very hard and sections are difficult to obtain. Sectioning quality will be improved and tissue component will be best preserved and demonstrated by gently facing the block and: a. soaking in water
b. warming the block slightly
c. soaking in a solution that softens keratin
d. treating with decalcifying fluid
c. soaking in a solution that softens keratin
The solution used in the knife tough when sectioning epoxy resins is usually:
water
a section of skeletal muscle has been frozen in isopentane and liquid nitrogen, but numerous holes are seen in H&E sections .this problem is casued by:
a. non-isometric fixed muscle tissue
b. sectioning too soon after freezing
c. leaving in isopepentane too long
d. isopentane that is not cold enough
d. isopentane that is not cold enough
must reach -150C to preven ice crystal artifacts= holes
“thick” sections for EM, or sections to be viewed with the light microscopy, are cut at:
0.5 to 1.0 um
Tissued to be sectioned with a cryostat may be somewhat protected from ice crystals artifacts by using:
infiltrating with 30% sucrose before freezing (also helps preserve membranes)
Glass knives suitable for cutting plastic blocks of medium hardness will have a cutting edge angle of:
45 degrees
During the sectioning of the plastic blocks with an ultramicrotome, no sections are being cut. The problem is most likely caused by:
a. dirt
b. dull knife
c. a loose knife
d. an incorrect water level
b. dull knife
Glass knives are being made for cutting ultra-thin sections. The time for obtaining good sections requires that these knives should be used within the same___ as being made:
a. hour
b. day
c. week
d. month
b. day
note: ultra-thin are usually cut on diamong knives at 90nm
diamond knives are used in ultramicrotomy because steel knives :
a. connot withstand the electron beam
b. leave steel shaving in ultrea-thin section
c. react with the chemicals in the resin blocks
d. are quickly dulled
d. are quickly dulled
grids used to support epoxy-embedded sections for Em are usually made from:
a. copper
b. iron
c. lead
d. zinc
a. copper
A microscopy section of liver tissue shows numerous irregular holes through the tissue. This is most likely because:
a. the holes are portal triads
b. liver is difficult to cut
c. fixation has been prolonged
d. sectioning technique was poor
d. sectioning technique was poor
Successive cryostat sections catch on one area in the middle of the anit-roll plate. The most likely cause is that the anti-roll plate is:
a. warmer than the knife
b. colder than the knife
c. improperly adjusted
d. damaged
d. damaged
bc succesful sections where obtained
Mayer egg albumin is observed to be contaminated with bacterial growth. the most probable explanation is that during preparation:
a. the reagent was inadequately heated
b. a non-sterile storage contained was
c. thymol was omitted
d. the eggs used in preparation were contaminated
c. thymol was omitted
thymol prevents microscopic growth in solutions
A ribbon of paraffin embedded brain tissue is floated on the water bath. small holes are noted on the first section that decrease in size in subsequent sections. The most appropriate action is to:
a. melt the block and re-embed the tissue
b. resharpen the knife
c. decrease the water bath temperature
d. cut and discard ribbons until the holes disappear
d. cut and discard ribbons until the holes disappear
this can is probably a paraffin bubble
Breathing on blocks during sectioning should be kept to a minimum when using:
a. celloidin
b. epon
c. paraffin wax
d. polyster wax
d. polyster wax
During fozen sectioning, the sections roll up and jam in front of the anti-roll plate. This is most likely due to the:
a. anti-roll plate being too low on the knife edge
b. anti-roll plate not being parallel to the edge of the knife
c. cryostat temperature being too low
d. space between the knife and the antiroll plate being too great
a. anti-roll plate being too low on the knife edge
which groups of abrasive compounds is used for microtome knife sharpening?
carborundum, diamond and jewel’s rouge
what is the main purpose of the flotation bath for paraffin ribbons?
warm water to relax the tissue and remove wrinkles/folds before placing it on a slide
