Questions from old exams 1-2

Washboarding observed in a section of uterus is most likely caused by which of the following?

loose or worn microtome parts

Agar, gelatin, and Elmer's glue are examples of:

Waterbath additives

In reference to microtomy, what is the clearance angle?

angle of blade in relation to the block face

Bevel angle is

the intersection of the two cutting facets of a microtome blade

A dull blade, too little clearance angle, paraffin accumulation behind the blade, and a warm block may all be causes of this microtomy artifact.

Compression

Melt down and re-embed

Microscopic evaluation of a colon section reveals only two layers.

Review of the paraffin block reveals additional tissue layers deeper in the block.

Which of the following is the best procedure for correction?

What causes this?

Slide not dried sufficiently

Which of the following methods for cleaning embedding molds is not recommended?

Using the cleaning cycle of the processor.

(is rec = boiling water, mold cleaning station, soaking in xylene)

Holes with ragged edges are seen in a section of liver when viewed microscopically. These were most likely caused by:

Aggressive sectioning

Small intestine should be embedded…

on edge

Incomplete drying can lead to..

wavy sections

Hydrate longer

When getting thick and thin sections, what is the first thing you should check?

Loose levers/clamps

The temperature of a waterbath should be how many degrees below the melting point of paraffin?

5-10 degrees

Waterbath too cool can cause what?

wrinkles

Which of the following is likely to cause sections to lift from the blade during microtomy?

clearance angle too low

Which of the following tissue types could contribute to washboarding or undulations?

dense, fibrous tissue

Rapid solidifying of paraffin at embedding is important for…

ensuring the best support for tissue

Which of the following artifacts is caused by contamination of the waterbath?

floaters

When sectioning dense fibrous tissue, what waterbath temperature adjustment may be necessary?

increase temp

Tissue debris

A ribbon will not form at sectioning. Which can be causes?

Improper clearance angle, dull/dirty blade, loose levers

Microchatter can be caused by…

underhydrated tissue

Holes/tears, cut less aggressively

Your sections keep lifting off the blade and sticking to the top of the block when cutting.

Which of the following would be a possible solution?

remove paraffin buildup

What tissue is susceptible to damage if too much pressure applied at embedding?

Brain

What do you put tissues in post fixation?

70% alcohol

Recommended temperature range for all methods that use heat for fixation, i.e. routine processing, primary microwave, and microwave assisted?

45-68

Which formalin solution should CNS tissues be put in?

Formalin ammonium bromide

All additive fixatives:

Chemically rx w/tissue molecules

fixative that penetrates slowly, but cross-links quickly

Glutaraldehyde

Cold ischemic time?

Time from removal from patient to placement in fixative

Formaldehyde is a poor fixative of…

nucleic acids

Formaldehyde penetration…

Pen fast, cross link slowly

Smudgy nuclei w/nuclear bubbling in mucosa is calused by

underfixation

Do not do fixation if ___ is needed.

immunoflourescence

Enzymatic destruction is called…

autolysis

Add copper acetate to fixatives to ___

Protect RBC lysis

e- microscopy pH

7.2-7.4

Which formalin solution is used as a dual purpose fixative for light and e- microsc.?

Modified Millonig formalin

used as a formaldehyde replacement due to lower toxicity and quicker fixation?

Glyoxal

Penetrates slowly, insolublizes lipids and oxidizes carbs?

Chromic acid

What fixative should be avoided for H. pylori demonstration?

Glyoxal

Fixative that lyses RBCs

Acetic acid

Chromate fixatives react with a specific cell type to form a pigment that cannot be prevented or removed in an effect called:

the chromaffin rxn

Chemical that is added to formaldehyde to prevent polymerization to paraformaldehyde?

Methanol

Picric acid ___

dissolves small calcifications

Coagulant fixatives…

denature proteins → Mesh like permeable network

What is a fix and a stain?

Picric acid

what is the maximum concentration of formaldehyde that can be achieved in water?

37-40%

What pigment cannot be prevented but can be removed?

Mercury

EM fixatives?

Paraformal., Osmium tetroxide, glutaraldehyde

A fixation pigment caused by chromate-containing fixatives can be prevented by treating the tissue with _______ prior to exposure to alcohol in processing.

Running water

Mercuric chloride is hazardous, but it produces..

exceptional nuclear detail

Acid hematin/formalin pigment is caused by…

acidic formalin (< 5.5-6)

A disadvantage of formaldehyde is…

it masks proteins antigens in immunohistochem staining

10% formalin contain ___% of formaldehyde?

3.7-4%

Non-coagulant

Which fixative category forms a gel-like network?

How does formaldehyde react with insoluble carbohydrates, nucleic acids, and lipids?

traps them in cross-linked proteins

Chromate fixation pigment can be partially removed with…

acidic alcohol

Formaldehyde ACTION

add., noncoag

Acetic acid ACTION

nonadd., coag

Zinc salts ACTION

add., coag

STEL (15 minutes short term exposure) for formaldehyde is…

< 2ppm

Soluble carbs are ___ during fixation

lost

Replacement for mercury?

Zinc salts

Specimen has remained in 10% NBF for a prolonged period of time. When an H&E slide from the specimen is examined microscopically, a black to dark brown pigment is observed adjacent to the RBCs.

Pigment cause?

Fixative becoming acidic

General function of fixatives?

Protect tissue against distortion during processing

Fixative for phospholipids?

Calcium formalin

Fixation for touch preps and blood smears

Desiccation

It is necessary to add buffer salts to formalin solutions to prevent:

formation of formalin pigment

Formalin pigment can be removed w/

alkaline alcohol

Nuclear bubbling is more commonly seen in tissue fixed in 10% formalin because it…

is a poor nuclear fixative

Microwave fixation is what type of fixation method?

Physical

Formaldehyde + water =

paraformaldehyde

Buffering formalin to a neutral pH is accomplished by adding…

sodium phosphate, monobasic and dibasic

Zinc chloride is the most preferred zinc salt due to a lower health risk.

T/F?

False

Zinc salt precipitation is caused by…

Phosphates in buffered formalin, carbs in water, heat/P/vacuum on processor

The change in the tertiary structure of proteins causing the molecule to become inactive and insoluble.

Denaturation

Fixative category that removes molecularly bound water from tissue

Nonadditive